Insights into channel modulation mechanism of RYR1 mutants using Ca2+ imaging and molecular dynamics.

Type 1 ryanodine receptor (RYR1) is a Ca2+ release channel in the sarcoplasmic reticulum in skeletal muscle and plays an important role in excitation-contraction coupling. Mutations in the RYR1 gene cause severe muscle diseases such as malignant hyperthermia (MH), which is a disorder of CICR via RYR1. Thus far, >300 mutations in RYR1 have been reported in patients with MH. However, owing to a lack of comprehensive analysis of the structure-function relationship of mutant RYR1, the mechanism remains largely unknown. Here, we combined functional studies and molecular dynamics (MD) simulations of RYR1 bearing disease-associated mutations at the N-terminal region. When expressed in HEK293 cells, the mutant RYR1 caused abnormalities in Ca2+ homeostasis. MD simulations of WT and mutant RYR1s were performed using crystal structure of the N-terminal domain (NTD) monomer, consisting of A, B, and C domains. We found that the mutations located around the interdomain region differentially affected hydrogen bonds/salt bridges. Particularly, mutations at R402, which increase the open probability of the channel, cause clockwise rotation of BC domains with respect to the A domain by alteration of the interdomain interactions. Similar results were also obtained with artificial mutations that mimic alteration of the interactions. Our results reveal the importance of interdomain interactions within the NTD in the regulation of the RYR1 channel and provide insights into the mechanism of MH caused by the mutations at the NTD.

Protection of Differentiating Neuronal Cells from Amyloid ß Peptide-induced Injury by Alkaline Extract of Leaves of Sasa senanensis Rehder.

BACKGROUND/AIM: We have previously reported the protection of doxorubicin-induced keratinocyte toxicity by alkaline extract of the leaves of Sasa senanensis Rehder (SE). In order to extend the generality of the cell protective effect of SE, we investigated whether it also protects rat PC12 and human SH-SY5Y neuron model cells from amyloid ß-peptide (Aß)-induced injury. MATERIALS AND METHODS: Viability of cells was determined by the MTT method. Cytotoxicity was evaluated by the concentration that reduces the cell viability by 50% (CC50). Protection from Aß-induced cytotoxicity was evaluated by the concentration that reversed the Aß-induced reduction of viability by 50% (EC50). The selectivity index (SI) of neuroprotective activity was defined as the ratio of EC50 to CC50 Aß1-42 aggregation was assayed using Aß1-42 ammonium hydroxide. RESULTS: SE showed hormetic growth stimulation at lower concentrations in both neuron precursors and differentiated cells. SE reproducibly inhibited Aß-induced cytotoxicity against both undifferentiated and differentiated neuron cells. Both the extent of differentiation induction and viability depended on the cell density, suggesting the release of growth and differentiation stimulation substances into culture supernatant. Higher concentrations of SE partially reduced the Aß1-42 aggregation. CONCLUSION: Hormetic growth stimulation and inhibition of aggregation may be involved in the neuroprotective activity of SE.

Biological effects of anti-RANKL antibody administration in pregnant mice and their newborns.

Denosumab, a fully human monoclonal antibody that neutralizes receptor activator of nuclear factor-κB ligand (RANKL) and blocks osteoclast differentiation, has received approval in Japan for use as an anti-resorptive drug for osteoporosis and skeletal-related events (SREs) in patients with solid cancer. Denosumab is contraindicated during pregnancy, though the effects of blocking RANKL activity on pregnant mothers and their newborns are unclear. We used mice to investigate the effects of an anti-RANKL antibody on maternal and newborn health. Mothers injected with the anti-RANKL antibody had increased bone mass as compared with the controls, while osteoclast number and the level of tartrate-resistant acid phosphatase (TRAP) in serum were increased at the end of pregnancy. Newborn mice exposed to the antibody in utero were normally born, but showed increased bone mass and died within 48 h after birth. None of the newborns were found to have milk in their stomachs, suggesting that they died due to a maternal defect in lactation. Consistent with this, anti-RANKL antibody-injected mothers displayed impaired mammary gland development. However, fostering by healthy surrogate mothers rescued only 33% of the antibody-exposed newborns, suggesting that neonatal mortality was due, at least in part, to an intrinsic defect in the newborns. Our findings show that anti-RANKL antibody administration during pregnancy results in not only an undesirable increase in bone mass, but also has harmful effects on newborn survival.

Genotype-Phenotype Correlations of Malignant Hyperthermia and Central Core Disease Mutations in the Central Region of the RYR1 Channel.

Type 1 ryanodine receptor (RYR1) is a Ca2+ release channel in the sarcoplasmic reticulum of skeletal muscle and is mutated in some muscle diseases, including malignant hyperthermia (MH) and central core disease (CCD). Over 200 mutations associated with these diseases have been identified, and most mutations accelerate Ca2+ -induced Ca2+ release (CICR), resulting in abnormal Ca2+ homeostasis in skeletal muscle. However, it remains largely unknown how specific mutations cause different phenotypes. In this study, we investigated the CICR activity of 14 mutations at 10 different positions in the central region of RYR1 (10 MH and four MH/CCD mutations) using a heterologous expression system in HEK293 cells. In live-cell Ca2+ imaging, the mutant channels exhibited an enhanced sensitivity to caffeine, a reduced endoplasmic reticulum Ca2+ content, and an increased resting cytoplasmic Ca2+ level. The three parameters for CICR (Ca2+ sensitivity for activation, Ca2+ sensitivity for inactivation, and attainable maximum activity, i.e., gain) were obtained by [3 H]ryanodine binding and fitting analysis. The mutant channels showed increased gain and Ca2+ sensitivity for activation in a site-specific manner. Genotype-phenotype correlations were explained well by the near-atomic structure of RYR1. Our data suggest that divergent CICR activity may cause various disease phenotypes by specific mutations.

Dataset of calcified plaque condition in the stenotic coronary artery lesion obtained using multidetector computed tomography to indicate the addition of rotational atherectomy during percutaneous coronary intervention.

Our data shows the regional coronary artery calcium scores (lesion CAC) on multidetector computed tomography (MDCT) and the cross-section imaging on MDCT angiography (CTA) in the target lesion of the patients with stable angina pectoris who were scheduled for percutaneous coronary intervention (PCI). CAC and CTA data were measured using a 128-slice scanner (Somatom Definition AS+; Siemens Medical Solutions, Forchheim, Germany) before PCI. CAC was measured in a non-contrast-enhanced scan and was quantified using the Calcium Score module of SYNAPSE VINCENT software (Fujifilm Co. Tokyo, Japan) and expressed in Agatston units. CTA were then continued with a contrast-enhanced ECG gating to measure the severity of the calcified plaque condition. We present that both CAC and CTA data are used as a benchmark to consider the addition of rotational atherectomy during PCI to severely calcified plaque lesions.

Regional calcified plaque score evaluated by multidetector computed tomography for predicting the addition of rotational atherectomy during percutaneous coronary intervention.

BACKGROUND: Rotational atherectomy (rotablation) has been proposed as a potentially superior strategy for percutaneous coronary intervention (PCI) in complex and severely calcified lesions. OBJECTIVES: We hypothesized that a per-lesion coronary artery calcium score determined by multidetector computed tomography (MDCT) would be useful for predicting the requriement for rotablation during PCI. METHODS: MDCT was performed in patients with stable angina pectoris who were scheduled for first PCI. In 116 consecutive subjects (168 target lesions) with successful PCI, MDCT and quantitative coronary angiography (QCA) data were retrospectively evaluated regarding their ability to predict rotablation. RESULTS: PCI without rotablation was performed in 105 patients (154 lesions), and rotablation was added in 11 patients (14 lesions). Patients with rotablation had significantly higher SYNTAX scores (p = 0.007) and total calcium scores (p < 0.001) than those without rotablation. Per-lesion, a lesion length ≥20 mm and diameter stenosis ≥74% on QCA as well as a per-lesion calcium score ≥453 and calcification arc ≥270 in MDCT predicted rotablation. After adjustment for potential confounding variables, a high per-lesion calcium score was an independent predictor of rotablation (odds ratio 31.3, 95% confidence interval 2.8-345, p = 0.005, sensitivity 93% and specificity 88%). CONCLUSION: The extent of target lesion calcification in MDCT, a simple marker of calcified plaque, is useful for predicting the need for rotablation during PCI.

Eribulin upregulates miR-195 expression and downregulates Wnt3a expression in non-basal-like type of triple-negative breast cancer cell MDA-MB-231.

Triple-negative breast cancer (TNBC), which does not show hormone sensitivity, is a poor prognosis disease without an established targeted treatment, so that establishing a therapeutic target for each subtype is desired. In addition, microRNA (miRNA), a non-cording RNA 19-25 nucleotide-longs in length, is known to be involved in regulating gene expression. We examined miRNA expression after exposure to eribulin, MDA-MB-231 cells, non-basal-like type of TNBC cell lines, and HCC1143 cells, basal-like type of TNBC cell lines. The activity of caspase-3 significantly increased compared to the control in MDA-MB-231, whereas no significant difference was observed in HCC1143. The expression level of 20-miRNAs significantly increased compared to the control in MDA-MB-231 after exposure to eribulin. The expression level of 6-miRNAs also significantly increased compared to the control in HCC1143. In these 2 cell types, miR-125b-1 and miR-195 were commonly expressed. While the expression level of miR-125b-1 decreased in both cells, the expression level of miR-195 increased in MDA-MB-231 and decreased in HCC1143. The expression level of miR-195 targeting Wnt3a significantly decreased compared to the control in MDA-MB-231, whereas it significantly increased in HCC1143. These results showed that exposure to eribulin highly increased the expression of miR-195 while it decreased the expression of Wnt3a in non-basal-like type of TNBC. Some miRNAs are known to regulate other signaling pathways involved in human pathogenesis by regulating the Wnt signaling pathway, and miRNA can act as a tumor-suppressing gene; therefore, miR-195 may serve as a therapeutic target in non-basal-like type of TNBC.

Reduced PTEN expression and overexpression of miR-17-5p, -19a-3p, -19b-3p, -21-5p, -130b-3p, -221-3p and -222-3p by glioblastoma stem-like cells following irradiation.

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a tumor suppressor gene that induces cell apoptosis by inhibiting the PI3K/Akt signaling pathway. Glioblastoma (GBM) is a brain tumor that is resistant to irradiation and chemotherapy and, thus, is difficult to cure. GBM stem-like cells (GSCs) have been implicated as a cause of this resistance. microRNA (miRNA/miR) inhibits the expression of proteins. The objective of the present study was to identify miRNAs that target PTEN, which induces apoptosis, in irradiation-resistant GSCs. When the expression of miRNAs was examined in GSCs irradiated at 60 Gy using the human GBM A172 cell line, the expression of PTEN-targeting miR-17-5p, -19a-3p, -19b-3p, -21-5p, -130b-3p, -221-3p and -222-3p was significantly higher in irradiated GSCs than in non-irradiated cells, and the PTEN expression levels, as revealed by immunostaining, were lower in the irradiated GSCs than in the non-irradiated cells. These results suggested that the expression of PTEN was suppressed through the overexpression of PTEN-targeting miRNAs in GSCs following irradiation.

Diabetes therapies in hemodialysis patients: Dipeptidase-4 inhibitors.

Although several previous studies have been published on the effects of dipeptidase-4 (DPP-4) inhibitors in diabetic hemodialysis (HD) patients, the findings have yet to be reviewed comprehensively. Eyesight failure caused by diabetic retinopathy and aging-related dementia make multiple daily insulin injections difficult for HD patients. Therefore, we reviewed the effects of DPP-4 inhibitors with a focus on oral antidiabetic drugs as a new treatment strategy in HD patients with diabetes. The following 7 DPP-4 inhibitors are available worldwide: sitagliptin, vildagliptin, alogliptin, linagliptin, teneligliptin, anagliptin, and saxagliptin. All of these are administered once daily with dose adjustments in HD patients. Four types of oral antidiabetic drugs can be administered for combination oral therapy with DPP-4 inhibitors, including sulfonylureas, meglitinide, thiazolidinediones, and alpha-glucosidase inhibitor. Nine studies examined the antidiabetic effects in HD patients. Treatments decreased hemoglobin A1c and glycated albumin levels by 0.3% to 1.3% and 1.7% to 4.9%, respectively. The efficacy of DPP-4 inhibitor treatment is high among HD patients, and no patients exhibited significant severe adverse effects such as hypoglycemia and liver dysfunction. DPP-4 inhibitors are key drugs in new treatment strategies for HD patients with diabetes and with limited choices for diabetes treatment.

Divergent Activity Profiles of Type 1 Ryanodine Receptor Channels Carrying Malignant Hyperthermia and Central Core Disease Mutations in the Amino-Terminal Region.

The type 1 ryanodine receptor (RyR1) is a Ca2+ release channel in the sarcoplasmic reticulum of skeletal muscle and is mutated in several diseases, including malignant hyperthermia (MH) and central core disease (CCD). Most MH and CCD mutations cause accelerated Ca2+ release, resulting in abnormal Ca2+ homeostasis in skeletal muscle. However, how specific mutations affect the channel to produce different phenotypes is not well understood. In this study, we have investigated 11 mutations at 7 different positions in the amino (N)-terminal region of RyR1 (9 MH and 2 MH/CCD mutations) using a heterologous expression system in HEK293 cells. In live-cell Ca2+ imaging at room temperature (~25 °C), cells expressing mutant channels exhibited alterations in Ca2+ homeostasis, i.e., an enhanced sensitivity to caffeine, a depletion of Ca2+ in the ER and an increase in resting cytoplasmic Ca2+. RyR1 channel activity was quantitatively evaluated by [3H]ryanodine binding and three parameters (sensitivity to activating Ca2+, sensitivity to inactivating Ca2+ and attainable maximum activity, i.e., gain) were obtained by fitting analysis. The mutations increased the gain and the sensitivity to activating Ca2+ in a site-specific manner. The gain was consistently higher in both MH and MH/CCD mutations. Sensitivity to activating Ca2+ was markedly enhanced in MH/CCD mutations. The channel activity estimated from the three parameters provides a reasonable explanation to the pathological phenotype assessed by Ca2+ homeostasis. These properties were also observed at higher temperatures (~37 °C). Our data suggest that divergent activity profiles may cause varied disease phenotypes by specific mutations. This approach should be useful for diagnosis and treatment of diseases with mutations in RyR1.

A new method for measuring osteoclast formation by electrical impedance.

Osteoclasts are important target cells for osteoporosis treatment. Recently, a real-time cell analysis (RTCA) system was developed to observe cell morphology and adhesion; however, the use of RTCA to study osteoclastogenesis has not been reported. Here, we investigated whether osteoclast formation could be monitored in real-time using RTCA. The cell index determined via electrical impedance using RTCA, and the number of osteoclasts exhibited a significant positive correlation. RTCA was useful for determining the effect of (-)-epigallocatechin-3-gallate on the inhibition of bone resorption. We established a new method of measuring osteoclast formation in real-time using RTCA.

Decreased miR-206 expression in BRCA1 wild-type triple-negative breast cancer cells after concomitant treatment with gemcitabine and a Poly(ADP-ribose) polymerase-1 inhibitor.

No targeted-therapy has been established for triple-negative breast cancer accompanied by mutations in breast cancer susceptibility gene1 (BRCA1) mutation. In the present study, using BRCA1 wild-type cells (MDA-MB-231) and BRCA1-mutated cells (MDA-MB-436), we investigated miRNA expression and apoptosis on day 1 after addition of gemcitabine-alone and in combination with poly ADP-ribose polymerase-1 (PARP1) inhibitor. After drug treatment, there were significantly fewer apoptotic BRCA1 wild-type cells than BRCA1-mutated cells. Expression of miRNA-26a, -29b, -100, and -148a increased in BRCA1 wild-type cells exposed to gemcitabine-alone and in combination with the PARP1 inhibitor. The addition of PARP1 inhibitor reduced miR-206 expression in BRCA1 wild-type cells but increased it in BRCA1-mutated cells. It was suggested that miR-206 serves as a target molecule of PARP1 inhibitor combination therapy for BRCA1 wild-type triple-negative breast cancer cells.

Anti-inflammatory effects of linagliptin in hemodialysis patients with diabetes.

Inflammation and glycemic control are important prognosis-related factors for hemodialysis (HD) patients; moreover, inflammation affects insulin secretion. Here, we evaluated the anti-inflammatory effects of monotherapy with linagliptin-a dipeptidase-4 inhibitor-in HD patients with type 2 diabetes. We examined 21 diabetic HD patients who were not receiving oral diabetes drugs or insulin therapy and with poor glycemic control (glycated albumin [GA] level, >20%). Linagliptin (5 mg) was administered to the patients daily. The levels of prostaglandin E2 (PGE2), interleukin-6 (IL-6), high-sensitivity C-reactive protein, GA, blood glucose, and active glucagon-like peptide-1 were determined before and 6 months after treatment. Body weight and serum levels of albumin, hemoglobin, total cholesterol, and low-density lipoprotein cholesterol were also recorded before and after treatment. The levels of PGE2 and GA were significantly decreased 1 month after starting linagliptin therapy, whereas the IL-6 levels were significantly decreased 6 months after starting linagliptin therapy. After 6 months of treatment, the PGE2 levels decreased from 188 ± 50 ng/mL to 26 ± 5 ng/mL; IL-6 levels, from 1.5 ± 0.4 pg/mL to 0.6 ± 0.1 pg/mL; and GA levels, from 21.3% ± 0.6% to 18.0% ± 0.6%. Glucagon-like peptide-1 levels increased 2.5-fold during the treatment. Over the 6-month treatment period, body weight and levels of high-sensitivity C-reactive protein, blood glucose, albumin, hemoglobin, and cholesterol did not change; none of the patients exhibited hypoglycemia. The anti-inflammatory effects of linagliptin monotherapy indicate that it may serve as a useful glucose control strategy for HD patients with diabetes.

Neuroprotective effects of propofol on ER stress-mediated apoptosis in neuroblastoma SH-SY5Y cells.

Anesthetic treatment has been associated with widespread apoptotic neurodegeneration in the neonatal rodent brain. It has recently been suggested that propofol, a short-acting intravenous anesthetic agent, may have a potential as a neuroprotective agent. An apoptotic pathway mediated through endoplasmic reticulum (ER) stress has been attracting attention. ER stress is associated with accumulation of unfolded or misfolded proteins in ER, and ER stress-induced apoptosis is implicated in a wide range of diseases, including ischemia/reperfusion injury, neurodegeneration, and diabetes. We investigated whether thapsigargin-induced ER stress is prevented by propofol in human neuroblastoma SH-SY5Y cells. SH-SY5Y cells were pretreated with various concentrations of propofol (1-10 µM) for 3h before co-treatment with 0.5 µM thapsigargin and propofol for 20 h. Levels of ssDNA, specific evidence of apoptosis, and biomarkers of ER stress (mRNA expression of Chop and sXbp-1) were determined. We also assayed calpain and caspase-4 activities and intracellular Ca(2+) ([Ca(2+)]i) levels. Thapsigargin-induced increases in ssDNA levels, expressions of ER stress biomarkers, activities of caspase-4 and calpain, and level of [Ca(2+)]i were suppressed by co-incubation with propofol. Our data indicate the possibility that propofol inhibits the Ca(2+) release from ER at clinically employed dose levels. These results demonstrate that propofol suppresses the ER stress-induced apoptosis in this cell system, and may have the neuroprotective potency. It may also be a promising agent for preventing damage from cerebral ischemia or edema.

Gene expression in the vascular wall of the aortic arch in spontaneously hypertensive hyperlipidemic model rats using DNA microarray analysis.

AIMS: In recent years, there has been an increase in patients with arteriosclerosis and the risk of lifestyle-related diseases. However, the pathogenesis and medication of atherosclerosis have not been elucidated. We developed a rat model of lifestyle-related diseases by feeding a high-fat diet and 30% sucrose solution (HFDS) to spontaneously hypertensive hyperlipidemic rats (SHHR) and reported that this model is a useful model of early atherosclerosis. In order to elucidate the pathogenesis of early atherosclerosis, we searched for atherosclerosis-related genes by microarray analysis using the aortic arch rat model of lifestyle-related diseases. MAIN METHODS: Four-month-old male Sprague-Dawley rats and SHHR were each divided into two normal diet (ND) groups and two HFDS groups. After a four-month treatment, the expression of mRNA in the aortic arch was detected using the oligo DNA microarray one-color method and quantified using real-time PCR. KEY FINDINGS: In this study, we detected 39 genes in microarray analysis. Esm1, Retnlb Mkks, and Grem2 showed particularly marked changes in gene expression in the SHHR-HFDS group. Compared with the SD-ND group, the SHHR-HFDS group had an increase in Mkks gene expression of about 26-fold and an approximately 22-fold increase in the expression of Grem2. Similarly, the expression of Esm1 increased by about 12-fold and that of Retnlg by about 10-fold as shown by quantitative real-time PCR. SIGNIFICANCE: This study suggested that these four genes might be important in early atherosclerosis development.

Long-term effects of alogliptin benzoate in hemodialysis patients with diabetes: a 2-year study.

AIM: To evaluate the long-term efficacy of monotherapy with the dipeptidase-4 inhibitor alogliptin benzoate in hemodialysis (HD) patients with type 2 diabetes. METHODS: Sixteen diabetic HD patients with inadequate glycemic control (hemoglobin A1c (HbA1c) level >6.5% and glycated albumin (GA) level >20%) on diet and exercise participated in the study. No patients were taking other oral antidiabetic drugs or receiving insulin therapy. Alogliptin 6.25 mg was administered to patients once daily. HbA1c, GA levels were obtained before and after 2 years of treatment. Body weight and active glucagon-like peptide-1, blood glucose, insulin, C-peptide immunoreactivity, glucagon, albumin, hemoglobin, and total cholesterol levels were also examined before and after treatment. RESULTS: Both HbA1c and GA levels decreased after starting alogliptin administration. As compared to the pretreatment levels, HbA1c and GA levels significantly decreased at 3 and 18 months, respectively, after starting alogliptin administration. HbA1c and GA levels decreased from 7.1 ± 0.2 to 5.8 ± 1.6% and from 22.5 ± 0.7 to 19.6 ± 0.6%, respectively, 24 months after beginning treatment. Glucagon-like peptide-1 levels (8.9 ± 5.7 pmol/l before treatment) doubled after treatment. Body weight and blood glucose, insulin, C-peptide immunoreactivity, glucagon, albumin, hemoglobin, and total cholesterol levels did not change with treatment. Only one significant adverse effect, a drug-related rash, was seen in 1 patient. CONCLUSION: Long-term (2-year) effects of alogliptin benzoate monotherapy suggest its efficacy as a new treatment strategy in diabetic HD patients.

Ethanol-induced apoptosis in human liver adenocarcinoma cells (SK-Hep1): Fas- and mitochondria-mediated pathways and interaction with MAPK signaling system.

For studying molecular mechanisms regulating the fate of ethanol-treated hepatocytes, involvement of Fas in ethanol-induced apoptosis was examined in human liver adenocarcinoma (SK-Hep1) cells in which the function of Fas-associated death domain (FADD) protein was knocked down by transfection. In FADD-knocked down cells, while ethanol-induced increase in generation of reactive oxygen species (ROS) was unaffected, apoptosis was significantly suppressed, demonstrating the involvement of Fas in ethanol-induced hepatocyte apoptosis more directly than in the past reports. On the other hand, effects of mitogen-activated protein kinase (MAPK), which is well known to determine the fate of various cells, on ethanol-induced apoptosis have not been examined in SK-Hep1 cells. Of three major MAPKs, only p38 MAPK and JNK were found activated by 200 mM ethanol treatment. When cells were incubated with inhibitors of p38 MAPK and JNK, ethanol-induced apoptosis was decreased while ROS generation was unaffected, and examination of pro-apoptotic Bax and anti-apoptotic Bcl-2 levels showed decrease of the former and increase of the latter. We concluded that oxidative stress inflicted by ROS triggered Fas-mediated and mitochondria-mediated apoptotic pathways in ethanol-treated SK-Hep1 cells, and that p38 MAPK and JNK were promoting mitochondrial pathway, suggesting interaction between apoptosis and MAPK signaling systems.

Gene analysis and dynamics of tumor stem cells in human glioblastoma cells after radiation.

Glioblastoma is the most malignant central nervous system tumor. Patients with glioblastoma are treated with a combination of surgery, radiotherapy and chemotherapy; however, this effect is not satisfactory with regard to the prognosis. It is reported that the tumor stem cells affect recurrence, and radio- and chemotherapy resistance of the tumor, and that these cells play an important role in tumorigenesis and tumor progression. Using human glioblastoma cell lines (T98G and A172), irradiated (0, 30, 60 Gy) glioblastoma cells were prepared under the same conditions as clinical therapy. We analyzed cell proliferation rate, side population analysis by fluorescence-activated cell sorting and isolation of CD133⁺ cells, and performed genetic analysis (human stem cells) on these cells. We also investigated the difference in gene expression in the cells after radiation. The stem cell-related genes were highly expressed in the CD133⁺ cells compared with the CD133⁻ cells, suggesting that the cancer stem cells may be located in these CD133⁺ cells. In the T98G cell line, the cell proliferation rate of 30-Gy irradiated cells was higher than those of non-irradiated cells and 60-Gy irradiated cells. Stem cell-related genes were highly expressed in 30-Gy irradiated CD133⁺ T98G cells. In conclusion, we suggest that CD133⁺ cells may strongly affect tumor proliferation and the resistance against radiation therapy.

Analysis of p53 and miRNA expression after irradiation of glioblastoma cell lines.

Glioblastoma is a malignant brain tumor that is difficult to completely cure by surgical treatment alone. However, resistance to anticancer drugs and radiation may be acquired during treatment. For instance, miRNAs involved in regulating the expression of genes inducing apoptosis and other specific genes have been proposed for use, in order to induce the apoptosis of radioresistant cancer cells. A172 glioblastoma cells, expressing wild-type p53 were irradiated to a total dose of up to 60 Gy allowing us to analyze the activities of apoptosis-related proteins. The miR-34a expression levels in cells after irradiation at 30 and 60 Gy were 0.17- and 18.7-times the BCL2 and caspase-9 expression levels, respectively. The high miR-34a expression level in the cells after irradiation at 60 Gy reduced the p53 expression level. This study suggests that apoptosis might be promoted by regulating the action of miRNAs, even in cells that have acquired radioresistance.