miR-124 regulates radiosensitivity of colorectal cancer cells by targeting PRRX1 / 南方医科大学学报

<p><b>OBJECTIVE</b>To detect the expression of miR-124 in colorectal carcinoma (CRC) cells and tissue specimens and analyze its association with the radiosensitivity of the cells.</p><p><b>METHODS</b>The expression of miR-124 in CRC cell lines and tissues were detected using qRT-PCR. The effect of miR-124 in modulating cell radiosensitivity was assessed in CRC cells with miRNA-124 overexpression and miRNA-124 knockdown, and bioinformatics prediction and dual luciferase reporter system were employed to identify the direct target of miR-124.</p><p><b>RESULTS</b>s miR-124 expression was down-regulated in CRC cell lines and tissues. CRC cells over-expressing miR-124 showed an obviously enhanced radiosensitivity, whereas miR-124 knockdown resulted in a reduced radiosensitivity of the cells. Bioinformatics prediction and dual luciferase reporter system verified PRRX1 as a direct target of miR-124, which regulated the radiosensitivity of CRC cells by directly inhibiting PRRX1.</p><p><b>CONCLUSION</b>miR-124 can enhance the radiosensitivity of CRC cells by directly targeting PRRX1, which provides a target for improving the therapeutic effect of radiotherapy of CRC.</p>

B-mode ultrasound for defining planning target volume in intensity-modulated radiotherapy for prostate cancer / 南方医科大学学报

<p><b>OBJECTIVE</b>To define the planning target volume (PTV) margins in intensity-modulated radiotherapy (IMRT) for prostate cancer without imaging guidance using B-mode acquisition and targeting (BAT) ultrasound-based prostate localization.</p><p><b>METHODS</b>Ten patients with prostate cancer underwent BAT ultrasound alignment before each IMRT session. The set-up deviations, each consisting of isocenter displacements in 3 directions (anterior-posterior, right-left lateral, and superior-inferior), were recorded for a total of 225 times and analyzed with Kolmogorov-Smimov (K-S) method.</p><p><b>RESULTS</b>The isocenter shift in each direction, which represented an average from all the patients, was 3.56∓2.71 mm, 4.08∓3.99 mm, and 3.20∓2.92 mm in the lateral (RL), anteroposterior (AP), and superior-inferior (SI) dimensions, respectively, and the deviations in each direction conformed to a normal distribution (P=0.806, P=0.061, and P=0.106, respectively). In the absence of imaging guidance for IMRT for prostate cancer, the PTV margin should expand by 8.97 mm in the right, 1.87 mm in the left, 12.05 mm in the anterior, 3.91 mm in the posterior, 9.06 mm in the superior and 2.66 mm in the inferior to allow 95% isodose curve to cover 90% of the clinical target volume.</p><p><b>CONCLUSION</b>The ultrasound imagining guided localization, with simple operation, nonirradiation and small systemic error, can be real-time corrected.</p>

Effect of gemcitabine in enhancing the radiosensitivity of HepG2 hepatoma cells and the possible mechanism / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the effect of gemcitabine in enhancing the radiosensitivity of hepatoma cell line HepG2 and explore its mechanisms.</p><p><b>METHODS</b>Clonogenic survival assay is employed to calculate the ratios of L-Q model radiation biology parameters and radiosensitization after different doses of irradiation. Flow cytometry was used to detect the changes in HepG2 cell cycle and apoptosis rate after gemcitabine treatment and radiation exposure.</p><p><b>RESULTS</b>The survival fraction at 2 Gy of HepG2 cells treated with gemcitabine was significantly lower, and the value of alpha was significantly higher than those of untreated cells. GEM treatment increased the percentage of radiation-induced G0/G1 phase cells and cell apoptosis.</p><p><b>CONCLUSION</b>Gemcitabine can significantly enhance the radiosensitivity of HepG2 cells by enhancing radiation-induced cell cycle arrest in G0/G1 phase and cell apoptosis.</p>

Ginsenoside Rg1 protects rat hippocampal neurons from radiation injury by regulating NOS activity / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the protective effect of ginsenoside Rg1 on cultured rat hippocampal neurons against radiation injury and explore new therapies for preventing radiation encephalopathy.</p><p><b>METHODS</b>Rat hippocampal neurons cultured for 12 days were subjected to a single-dose X-ray exposure of 30 Gy. 4',6-diamidino-2-phenylindole (DAPI) staining was used to detect the neuronal apoptosis and NOS activity kit utilized to evaluate NOS activity in the cells after the exposure.</p><p><b>RESULTS</b>Nuclear condensation was detected in (25.3-/+3.57)% of the neurons 24 h after 30 Gy X-ray exposure, a rate significantly higher than that in the control cells [(1.95-/+0.78)%, P<0.01]. In the neurons pretreated with ginsenoside Rg1, only (7.43-/+1.51)% of the cells presented with nuclear condensation after the exposure, significantly different from the rates in the control cultures and the exposed cultures (P<0.01). The NOS activity of exposed cultures was 6.46-/+0.95 U/ml, significantly higher than that in the control cultures (3.20-/+0.70 U/ml, P<0.01). The NOS activity of the neurons pretreated with ginsenoside Rg1 was 3.85-/+0.69 U/ml, significantly different from that in the control cultures (P<0.05) and the exposed cultures (P<0.01).</p><p><b>CONCLUSION</b>Ginsenoside Rg1 offers significant protective effect on rat hippocampal neurons from radiation-induced apoptosis by reducing the activity of NOS.</p>

Effect of NAD+ against radiation injury and its dose-effect relationship / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the effect of NAD+ against radiation injury and its dose-effect relationship.</p><p><b>METHODS</b>L02 liver cells cultured in RPMI 1640 medium containing 10% fetal calf serum were exposed to X-ray irradiation followed by immediate application of NAD+. The cellular viability was analyzed by MTT assay and the apoptotic cells were detected by TUNEL methods to observe the damages of L02 liver cells induced by X-ray exposure and analyze the dose-effect relationship of NAD+.</p><p><b>RESULTS</b>The viability of L02 liver cells was decreased with increasing dose of X-ray irradiation. The most obvious growth inhibition of L02 cells occurred 24 h after the irradiation. NAD+ significantly increased the cell survival rate after irradiation, and this effect was gradually increased within the concentration range of 100-1000 microg/ml; at higher concentrations, the survival rate of the irradiated L02 cells showed no significant increase.</p><p><b>CONCLUSION</b>NAD+ provides partial protection of the liver cells against radiation injury, and the effect is positively correlated to NAD+ concentration within a certain range.</p>

Effects of radiosensitivity and X-ray dose on miR-7 expression in nasopharyngeal carcinoma / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effects of radiosensitivity and X-ray dose on the expression of miR-7 in nasopharyngeal carcinoma (NPC) cells.</p><p><b>METHODS</b>Low radiosensitive NPC cells CNE-1 and high radiosensitive NPC cells CNE-2 were exposed to 0, 2 and 8 Gy X-ray. The total RNAs of the cell lines were extracted 10 h after radiation for reverse transcription of miR-7 and 18S rRNA by stem-loop primer and random hexamers, respectively. The non-irradiated CNE-1 cells served as the control sample and the relative quantity of the expression level was calculated after real-time PCR using SyBR green.</p><p><b>RESULTS</b>miR-7 expression differed significantly between CNE-1 and CNE-2 cells (4.49-/+3.62 vs 1.29-/+1.10, F=135.483, P<0.001). The radiation dose also significantly affected the expression of miR-7 in NPC cells (F=39.565, P<0.001). CNE-1 cells with a 2 Gy exposure had the highest expression level of miR-7, while the non-irradiated CNE-1 cells had the lowest expression. CNE-2 cells exposed to 2 Gy X-ray had the lowest expression level of miR-7 and the non-irradiated CNE-2 cells had the highest.</p><p><b>CONCLUSION</b>Radiosensitivity and radiation dose of X-ray have significant effect on the expression of miR-7 in NPC cells, indicating that miR-7 plays an important role in radioresistance of NPC cells to X-ray, and suppressed miR-7 expression may elevate the radiosensitivity of NPC cells.</p>

MicroRNA profiling in patients with hepatocellular carcinoma / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the differential expression of microRNAs between human hepatocellular carcinoma (HCC) and liver cirrhosis (LC).</p><p><b>METHODS</b>The total RNA was extracted from 25 pairs of HCC and LC tissues. microRNA microarray was used to analyze the microRNA expression profiles, and validation of the microarray results was carried out by real-time quantitative RT-PCR (qRT-PCR).</p><p><b>RESULTS</b>Three microRNAs exhibited higher expression in the HCC samples than in the LC samples. In comparison with the LC samples, the HCC samples showed down-regulated expressions of 9 microRNAs. qRT-PCR verified that has-miR-122a, has-miR-199a, and has-miR-199b were downregulated in HCC, which was in agreement with the microarray results.</p><p><b>CONCLUSION</b>HCC and LC samples have significantly different microRNA expression profiles. These differentially expressed microRNAs may be involved in the pathogensis of HCC.</p>

Role of lung fibroblast activation in radiation lung injury / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the role of lung fibroblast activation in radiation-induced lung injury.</p><p><b>METHODS</b>Thirty-five male Wistar rats were exposed to a single-dose 30 Gy irradiation of the right hemithorax or sham right lung irradiation. At 1, 7, 14, 28, 56 or 84 days after the irradiation, the rats were sacrificed for examination of alpha-smooth muscle actin (alpha-SMA) expression in the bilateral lung tissues using immunohistochemistry.</p><p><b>RESULTS</b>alpha-SMA expression in fibroblast increased significantly in the out-field and in-field lung tissues within 24 h after irradiation after the irradiation (P<0.001).</p><p><b>CONCLUSION</b>Activation of the lung fibroblasts occurred within 24 h after irradiation and found in ont-field and in-field lung tissues, suggesting that radiation-induced lung injury may not have an obvious latency.</p>

Determination of the repair half-time of human nasopharyngeal carcinoma cell lines CNE1, CNE2, HONE1 and C666-1 / 南方医科大学学报

<p><b>OBJECTIVE</b>To determine the repair half-time (T1/2), a speed parameter of sub-lethal damage repair (SLDR), of human nasopharyngeal carcinoma (NPC) cell lines CNE1, HONE1, C666-1 and CNE2.</p><p><b>METHODS</b>A total radiation dose of 8 Gy divided into 4+4 Gy was delivered to the cell lines at the interval of 0 s, 15 s, 30 s, 1 h, 2 h, 4 h or 6 h. The cell survival fractions were determined using the standard cell clonogenic assay. The curves of the changes in the surviving cell fraction after a total dose of 8 Gy, as a function of the interval between the two doses of 4 Gy, were fitted manually, and the T1/2 of each cell line was calculated according to the curves.</p><p><b>RESULTS</b>The T1/2 of CNE1, HONE1, C666-1 and CNE2 were 18 s, 22 s, 29 s and 27 s, respectively.</p><p><b>CONCLUSION</b>The speed of SLDR of NPC cells is quite rapid, indicating that the fraction delivery time longer than 20 s might decrease the effect of radiotherapy.</p>

p35 and p25 expressions and Cdk5 kinase activity in primary cultured rat hippocampal neurons with X-ray exposure / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the expressions of p35 and p25 and Cdk5 kinase activity in cultured rats hippocampal neurons following X-ray exposure to provide experimental evidence for prevention and treatment of radiation encephalopathy.</p><p><b>METHODS</b>The hippocampal neurons cultured for 12 days were subjected to a single-dose X-ray exposure of 30 Gy. Western blotting was used to detect the p35 and p25 protein levels, and the effect of pretreatment with roscovitine, a Cdk5 inhibitor, on the apoptosis of the hippocampal neurons following the exposure was examined with 4',6-diamidino-2-phenylindole (DAPI) staining.</p><p><b>RESULTS</b>The protein level of p35 increased significantly 3.5 and 4 h after the irradiation by 1.51-/+0.13 and 1.45-/+0.14 folds in comparison with the control level, respectively (P<0.01), and the p25 level increased significantly 6 h after irradiation by 1.62-/+0.28 folds (P<0.05). Nuclear condensation occurred in (24.8-/+3.97)% of the neurons 24 h after 30 Gy X-ray exposure, a rate significantly higher than that in the nonexposed cells [(1.82-/+1.08)%, P<0.01) and that in roscovitine-pretreated neurons [(7.74-/+2.27)%, P<0.01).</p><p><b>CONCLUSION</b>X-ray exposure activates Cdk5 by increasing the p35 and p25 expressions in rat hippocampal neurons, and inhibition of Cdk5 activity with roscovitine can significantly protect the neurons from apoptosis.</p>

Expressions of metastatic tumor antigen 1 and hypoxia-inducible-factor l alpha in lung cancer and their clinical significance / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the correlation of the expressions of metastatic tumor antigen 1 (MTA1) and hypoxia-inducible-factor l alpha (HIF-1alpha) to the clinical features of lung cancer.</p><p><b>METHODS</b>The expressions of MTA1 and HIF-1alpha proteins in 59 lung cancer patients were detected by immunohistochemistry.</p><p><b>RESULTS</b>Positive staining of MTA1 and HIF-1alpha was found in 54.24% and 50.85% of the patients, respectively. MTA1 expression was not found to correlated to any of the clinical parameters. HIF-1alpha expression was significantly lower in poorly differentiated than in moderately and well differentiated lung cancer (P<0.05), and a positive association between the expressions of MTA1 and HIF-17alpha were noted (P<0.05).</p><p><b>CONCLUSION</b>MTA1 and HIF-1alpha overexpression occurs in lung cancer possibly as an important factor of lung carcinogenesis. MTA1 may promote lung carcinogenesis by enhancing HIF-1alpha protein activity.</p>

Effect of X-ray exposure on soluble tumor necrosis factor receptor-p75 release in hepatocellular carcinoma HepG2 cells in vitro / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effects of X-ray exposure on the release of soluble tumor necrosis factor receptor-p75 (sTNFR-p75) in hepatocellular carcinoma HepG2 cells in vitro.</p><p><b>METHODS</b>Enzyme-linked immunosorbent assay (ELISA) was used to examine the levels of sTNFR-p75 in the supernatants of HepG2 cells before and after X-ray exposure. The cell apoptosis was analyzed by flow cytometry and transmission electron microscope(TEM), and the morphological changes of the cells were examined under optical microscope and transmission electron microscope(TEM).</p><p><b>RESULTS</b>X-ray exposure of the cells resulted in a strong increase of cell apoptosis (P<0.05) and sTNFR-p75 production in the cells as compared with the those before the exposure (P<0.01). Optical microscopy revealed apoptotic changes of HepG2 cell after the exposure, shown as cell shrinkage, spherical cell morphology, cytoplasmic and nuclear condensation. Apoptotic bodies were detected by TEM.</p><p><b>CONCLUSION</b>X-ray exposure induces HepG2 cells apoptosis by inhibiting the release of sTNFR-p75 into the supernatant.</p>

Three-dimensional conformal radiotherapy combined with transcatheter arterial chemoembolization for massive primary liver cancer / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the outcomes of patients with unresectable massive primary liver cancer (PLC) receiving three-dimensional conformal radiotherapy (3-DCRT) combined with transcatheter arterial chemoembolization (TACE).</p><p><b>METHODS</b>From January 2001 to December 2004, 84 patients with unresectable massive PLC (tumor size> or =10 cm) received 3-DCRT combined with TACE, including 49 cases in UICC/AJCC T(3) stage and 35 cases in T(4) stages. Lymph node metastasis was found in none of the patients, and portal vein tumor thrombosis (PVTT) was detected in 30 cases. Child-Pugh grade A of liver cirrhosis was present in 64 cases and grade B in 20 cases. The mean value of GTV was 705-/+430 cm(3) (170-2099 cm(3)). Following injections of fluorouracil and hydroxycamptothecine into the target artery of the tumor, the mixture of carboplatin, mitomycin (or pirarubicin) and super-liquefactive iodized oil was injected into the target artery. Gelatin sponge was used to embolize the artery. The procedure was repeated every 1.5-2 months according to the condition of the patients, and each patient received 1-3 such procedures. 3-DCRT was performed in all the patients, who received a total dose of 53.6-/+6.6 Gy (4-6 Gy per fraction at the interval of 48 h), and 3 fractions were given every week.</p><p><b>RESULTS</b>Eight patients died in 3 months after 3-DCRT and were not evaluated. The total response rate (CR+PR) in these patients was 68.9% (51/74). The overall survival rates at 1, 2 and 3 years were 55.4%, 24.7% and 15.4%, respectively. T stage, GTV, PVTT and fraction size had no significant impact on the overall survival. Child-Pugh grade was found to have significant impact on the patients' survival (P=0.035, RR=2.440).</p><p><b>CONCLUSION</b>3-DCRT combined with TACE has definite therapeutic effect on advanced massive PLC, and Child-Pugh grade is an independent prognostic factor in such cases.</p>

Enhancement of HepG2 cell radiosensitivity by mutant IkappaBalpha gene transfection / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the efficacy of transfection with a mutant IkappaBalpha gene (mIkappaBalpha) in enhancing the radiosensitivity of hepatocellular carcinoma cells.</p><p><b>METHODS</b>The hepatocellular carcinoma Hep G2 cells were divided into 3 group and transfected with the adenovirus containing mIkappaBalpha vector (Ad-mIkappaBalpha group), Ad vector (Adv group), or without treatment (parental control cells). Before and after irradiation of the cells with 6 Gy high-energy X ray, Western blotting was performed to measure the expression level of IkappaBalpha in the cytoplasm, and electrophoresis mobility shift assay (EMSA) carried out to evaluate the nuclear factor-kappaB (NF- kappa;B) activity in the cell nuclei, with the cell apoptosis detected using TUNEL assay. The radiosensitivity of the HepG2 cells were determined by comparison between the 3 groups in term of the surviving cell fractions (SF2) after 2-Gy X-ray exposure, and of the Do and Dq values obtained using the single-hit multi target model.</p><p><b>RESULTS</b>Before the X-ray exposure, the Hep G2 cells in Adv group and the control group showed low levels of IkappaBalpha absorbance in the cytoplasm, which were further decreased after the exposure. The NF-kappaB activity in the nuclei of the cells in the two groups was positive (+) before irradiation, and substantially enhanced (++) after the exposure and maintained the stably activated state. The apoptotic index of the cells in the two groups was 1.4 and 1.6 before irradiation, and increased to 8.9 and 11.7 after the irradiation, respectively. The cells in the Ad-mIkappaBalpha group, however, exhibited high levels of IkappaBalpha absorbance either before or after the irradiation, which were approximately 3 times that of the Adv group, but the NF-kappaB activity remained negative irrespective of the irradiation. The apoptotic index of the cells in the Ad-mIkappaBalpha group was 18.2 before irradiation, was increased to 88.3 after the irradiation. Among the 3 groups, Ad-mIkappaBalpha group had the smallest SF(2) value of 0.301 but the highest sensitivity enhancement ratio (SER) of2.99, with the lowest Do and Dq values (1.468 and 0.709, respectively).</p><p><b>CONCLUSION</b>mIkappaBalpha gene transfection into HepG2 cells inhibits the anti-apoptotic activity of NF-kappaB to enhance the radiosensitivity of the cells.</p>

Expression of PCNA and GST-pi after stereotactic irradiation for liver cirrhosis and hepatocarcinoma in rabbits / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe the changes of the cytokines following stereotactic irradiation for hepatocarcinoma with cirrhosis in rabbits.</p><p><b>METHODS</b>Sixteen rabbits with liver cirrhosis and hepatocarcinoma (experimental group) were randomized into two equal groups to receive stereotactic irradiation at single dose of 20 and 30 Gy, respectively. Eight rabbits with hepatocarcinoma (control group) were divided into two equal groups and treated in identical manner. All the rabbits were killed 3 weeks after irradiation, and EV two-step method was used to observe the cytokine changes of proliferating cell nuclear antigen (PCNA) and glutathione S-transferase pi (GST-pi) after irradiation.</p><p><b>RESULTS</b>After irradiation, PCNA and GST-pi expression showed significant difference in the adjacent liver tissue between the experimental and control rabbits with irradiation at 20 Gy (P=0.010), but not with the irradiation dose of 30 Gy (P=1.000). Irradiation at different doses resulted in significant difference in the cytokine expression in the experimental rabbits (P=0.010). In the liver tissue exposed to irradiation, different irradiation doses resulted in significant difference in PCNA and GST-pi protein expression (P=0.010).</p><p><b>CONCLUSIONS</b>For hepatocarcinoma with cirrhosis in rabbits, radiation at the single dose of 30 Gy produces better response than 20 Gy, and PCNA and GST-pi may serve as good indexes for evaluating the therapeutic effect.</p>

Reduced irradiation target volume of mediastinal lymph node drainage in conformal radiotherapy for patients with non-small cell lung cancer after thoracic surgery / 南方医科大学学报

<p><b>OBJECTIVE</b>To decrease lung and esophageal radiation injuries by reducing irradiation target volume of mediastinal lymph mode drainage in conformal radiotherapy (CRT) for patients with non-small cell lung cancer (NSCLC) after thoracic surgery.</p><p><b>METHODS</b>Fifty-three patients with NSCLC were randomized into groups A and B to receive 3D-CRT after thoracic surgery. Patients in group A, according to conventional therapy, received preventive nodal irradiation (PNI) of the mediastinal lymph node drainage, and those in group B, according to pathological nodal staging after operation, did not have PNI of the metastasis-free area to reduce the clinical target volume (CTV). Patients in both groups were treated with conventional fractionated radiotherapy (CFRT) at 2 Gy in each fraction, and 5 fractions each week. All patients were followed up for two years to record their 2-year survival rate, local relapse of lymph node drainage and lung and esophageal radiation injuries.</p><p><b>RESULTS</b>The total 2-year survival rate was 58.5%in these patients and comparable between the two groups. The rates of local regional relapse and recurrence out of the CTV were 13.8% and 3.4% in group A and 16.7% and 8.3% in group B, respectively (P=1 and P=0.571). The incidence of radiation pneumonia and lung fibrosis were 6.9% and 62.1% in group A and 0% and 58.3% in group B (P=0.459 and P=0.782), and that of radiation esogphagitis and esophagus stricture rates were 27.6% and 6.9% in group A and 12.5% and 4.2% in group B, respectively (P=0.039 and P=1).</p><p><b>CONCLUSION</b>Reduced CTV does not warrant decrease in the local control but may lower the incidence of acute esophageal radiation injury in postoperative patients with NSCLC.</p>

CT manifestation in comparison with histopathological findings of radiation-induced liver disease in pigs: a pilot study / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the pathological basis of radiological reaction types of radiation-induced liver disease on multiphasic CT scans.</p><p><b>METHODS</b>Three pigs (tagged with A, B, and C) were subjected to single-dose radiation of 40, 40 and 30 Gy on the right or left lobe of the liver, respectively. At 42, 56, 133, and 168 days after irradiation, all pigs were examined with non-enhanced scan and contrast-enhanced scans at different time points after contrast injection. Hounsfield units (HU) were measured in each CT study to evaluate the density of irradiated and non-irradiated liver tissue to determine the reaction type. Liver tissues in the irradiation area obtained by needle biopsy with CT guidance were examined with electron microscopy, and specimens of the tissue corresponding to the region of interest on CT were obtained from necropsies for pathological examination.</p><p><b>RESULTS</b>Radiologically, the 3 pig models presented with 3 reaction types on the multiphasic CT scans on days 133, 56, and 168 after radiation, respectively. Type 1 presented constant low-density change in all phases, the pathological basis of which was radiation hepatitis; type 2 showed pre-contrast phase isodense, arterial phase hyperdense, portal phase isodense and later phase hyperdense changes; type 3 was characterized by pre-contrast phase isodense, arterial phase hyperdense, portal phase hypodense and later phase hyperdense changes. The pathological basis of the last two radiological reaction types was radiation cirrhosis (postnecrotic cirrhosis).</p><p><b>CONCLUSIONS</b>Different radiological reaction types of radiation liver injury on multiphase CT have different pathological basis, and multiphase contrast-enhanced CT may help distinguish the radiation reactions from tumor recurrence.</p>

Relationship between radiosensitivity of nasopharyngeal carcinoma and MDR1 gene polymorphism / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the relationship between human multidrug resistancel gene (MDR1) polymorphisms and the radiosensitivity of nasopharyngeal carcinoma (NPC).</p><p><b>METHODS</b>Blood samples were collected from 59 NPC patients, who were devided into radiosensitive or radioresistant groups according to their responses to radiation therapy. The genotypes for MDR1 polymorphisms (G2677T in exon 21 and C3435T in exon 26) and their haplotypes were determined by PCR and restriction fragment length polymorphism analysis. The results were further confirmed by sequencing.</p><p><b>RESULTS</b>The 3435CC genotype was associated with a significantly better response to radiotherapy than combined 3435 CT and TT genotype (P=0.026). The 2677GG genotype was also associated with a better response in comparison with combined 2677 GT and TT genotype, but this relation was not statistically significant. Patients with 2677G-3435C haplotype had a significant better response to radiotherapy than those with the other haplotypes (P=0.017).</p><p><b>CONCLUSION</b>The MDR1 G2677T and C3435T polymorphisms may help predict the response to radiotherapy in NPC patients.</p>

Rna interference of annexin II gene in PC3 cells by using small interference RNA synthesized with in vitro transcription / 中国医学科学杂志(英文版)

<p><b>OBJECTIVE</b>To silence annexin II gene expression by using small interference RNA (siRNA) in prostate cancer cell line PC3.</p><p><b>METHODS</b>For in vitro transcription, four sequences of 29-nucleotide DNA template oligonucleotides were designed, and one pair of the sequences were complementary to annexin II gene. The other pair was negative control. The 8 nucleotides at the 3' end of each oligonucleotide were complementary to the T7 Promoter Primer. The sense and antisense siRNA templates were transcribed by T7 RNA polymerase and the resulting RNA transcripts were hybridized to create dsRNA. The siRNA was transfected into prostate cancer cell PC3. For assaying the efficiency of siRNA, confocal microscopy, Northern blotting, and Western blotting were employed to examine the expression of annexin II protein and its mRNA. 3H thymidine was used to measure DNA synthesis.</p><p><b>RESULTS</b>The siRNA sequence specific to annexin II gene was capable of inhibiting the expression of annexin II protein and its mRNA. And cellular DNA synthesis was significantly reduced in siRNA transfected cells.</p><p><b>CONCLUSIONS</b>The protocol for the synthesis of siRNA by T7 RNA polymerase is feasible. Annexin II might be involved in DNA synthesis.</p>

Assessment of radiation-induced liver injury with computed tomography / 南方医科大学学报

<p><b>OBJECTIVE</b>To review the appearance of radiation-induced liver injury on computer tomography for quantitative assessment of dosimetric changes in different radiological reactions and the influence of time-effect.</p><p><b>METHODS</b>The focal liver reactions of 35 patients treated with three-dimensional conformal radiation therapy (3-D CRT) for liver malignancies were evaluated, with the applied doses of 36-65 Gy in 4-28 fractions completed in 8-41 days. All patients received nonenhanced CT scan and arterial-dominant phase contrast-enhanced CT scan 1-6 months after therapy. The liver tissue density in irradiated and nonirradiated liver was compared, and the reaction type and the threshold dose determined radiologically.</p><p><b>RESULTS</b>On at least one follow-up examination, 51.4% of patients were found to have a focal radiation reaction in the liver. The radiation reaction was hypodense in 43.75% of the follow-up nonenhanced CT examinations and in 19.23% of arterial-dominant phase contrast-enhanced CT scans. It was hyperdense in 42.31% of arterial-dominant phase contrast-enhanced CT scans. The median threshold dose inducing a radiation reaction was 30.8 Gy (range 18-42.8 Gy). The detected threshold dose was positively correlated with the time of detection of the reaction (P=0.041), with a correlation coefficient of -0.473. On arterial-dominant phase contrast-enhanced CT scans, the threshold dose was significantly higher for hyperdense than for hypodense changes (P=0.017). In additional follow-up, the reaction volume decreased and the reaction types changed on arterial-dominant phase contrast-enhanced CT scans.</p><p><b>CONCLUSIONS</b>The threshold dose can be different in different radiological reaction types on multiphase CT scans. The detected threshold dose is inversely correlated with the time of detection of the early reaction. Multiphase contrast-enhanced CT is helpful to distinguish radiation reactions from recurrent tumors.</p>