Histone methyltransferase SETDB1 promotes colorectal cancer proliferation through the STAT1-CCND1/CDK6 axis.

Upregulation of histone methyltransferase SET domain bifurcated 1 (SETDB1) is associated with poor prognosis in cancer patients. However, the mechanism of oncogenicity of SETDB1 in cancer is hitherto unknown. Here, we show that SETDB1 is upregulated in human colorectal cancer (CRC) where its level correlates with poor clinical outcome. Ectopic SETDB1 promotes CRC cell proliferation, whereas SETDB1 attenuation inhibits this process. Flow cytometry reveals that SETDB1 promotes proliferation by driving the CRC cell cycle from G0/G1 phase to S phase. Mechanistically, SETDB1 binds directly to the STAT1 promoter region resulting in increased STAT1 expression. Functional characterization reveals that STAT1-CCND1/CDK6 axis is a downstream effector of SETDB1-mediated CRC cell proliferation. Furthermore, SETDB1 upregulation is sufficient to accelerate in vivo proliferation in xenograft animal model. Taken together, our results provide insight into the upregulation of SETDB1 within CRC and can lead to novel treatment strategies targeting this cell proliferation-promoting gene.

Diagnostic value of serum squamous cell carcinoma antigen for hepatocellular carcinoma: a systematic review and meta-analysis.

The aim of this study was to ascertain the diagnostic value of serum squamous cell carcinoma antigen (SCCA) and SCCA-IgM for hepatocellular carcinoma (HCC). After a comprehensive search of PubMed and Web of Science databases, we identified eligible studies on the diagnostic value serum SCCAs for HCC. The quality of the eligible studies was assessed using the revised Quality Assessment for Studies of Diagnostic Accuracy (QUADAS-2) tool. The overall diagnostic value of SCCAs for HCC was pooled using a bivariate model. Twelve studies were included in this systematic review and meta-analysis. The pooled sensitivities for SCCA and SCCA-IgM were 0.61 (95% confidence interval [CI], 0.37-0.81) and 0.70 (95% CI, 0.55-0.82), respectively. The corresponding specificities were 0.80 (95% CI, 0.52-0.94) and 0.62 (95% CI, 0.51-0.72), respectively. The areas under summary receiver operating characteristic (sROC) curves for SCCA and SCCA-IgM were 0.76 (95% CI, 0.72-0.80) and 0.70 (95% CI, 0.66-0.74), respectively. Major design deficiencies of the included studies were two-gate design and partial verification bias. Therefore, we concluded that both serum SCCA and SCCA-IgM have a fair diagnostic value for HCC.

Correlation between expression of thymidylate synthase and clinical outcome of advanced gastric cancer treated with capecitabine alone chemotherapy.

Thymidylate synthase (TS) is a prognostic marker in various tumors. However, the results of previous investigations in gastric cancer (GC) were controversial. The objective of this article is to investigate whether TS expression is associated with clinical outcome in advanced GC receiving capecitabine alone chemotherapy. The study reviewed 58 cases of advanced GC in patients aged ≥65 years between December 2008 and June 2012. All patients were treated with capecitabine alone chemotherapy. Immunohistochemical staining for TS protein expression was performed. The relationships between TS expression and clinicopathological characteristics (included age, gender, number of metastatic sites, Eastern Cooperative Oncology Group (ECOG) score, differentiation, and lymph node metastatic status), chemotherapy response, progression-free survival (PFS), and overall survival (OS) were evaluated. There was no association between TS expression and age, gender, number of metastatic sites, ECOG score, differentiation, and lymph node metastatic status (P > 0.05). The chemotherapy response rates among patients with low- and high-level expression of TS protein were 52.0 % (13/25) and 21.2 % (7/33), respectively (χ (2) = 5.968, P = 0.015). The median PFS and OS in patients with low-level TS expression were significantly longer than those with high-level TS expression (PFS 8.0 vs 2.8 m, P = 0.001; OS 13.3 vs 7.9 m, P = 0.002, respectively). Multivariate Cox regression analysis revealed that TS expression was independent risk factor for OS (hazard ratio (HR) 0.237; 95 % confidence interval (CI) 0.108 to 0.520; P = 0.000). The present study demonstrates that TS expression is associated with chemotherapy response, PFS, and OS in advanced GC patients treated with capecitabine alone chemotherapy.

Overexpression of DcR3 and its significance on tumor cell differentiation and proliferation in glioma.

BACKGROUND: Overexpression of decoy receptor 3 (DcR3) have been reported in various classes of malignancies. However, its expression and clinicopathological contribution in gliomas has not been fully elucidated. OBJECTIVE: To explore the expression and clinical significance of DcR3 protein in relation to tumor cell differentiation and proliferation in glioma cell lines and tissues. METHODS: One hundred and twenty-five samples of glioma patients and 18 cases of normal brain tissues were recruited. The expression of DcR3 protein was detected using immunohistochemistry. Tumor differentiation was assessed by histologic characters and the status of glial fibrillary acidic protein (GFAP). Tumor cell labeling indexes (LIs) of Ki-67 and PCNA were also obtained. The relationship between the DcR3 level and clinicopathological features was investigated, including tumor differentiation, LIs, and survival. Meanwhile, the expression of DcR3 protein was also measured in the supernatants of 8 glioma cell lines and glioma cells freshly prepared from 8 human glioblastoma specimens by using western blot. RESULTS: The level of DcR3 protein in gliomas was significantly higher than that in normal brain tissues (P < 0.01). DcR3 expression showed positive correlations with tumor pathological grade (r = 0.621, P < 0.01) and negative with GFAP expression (r = -0.489, P < 0.01). Furthermore, there were positive correlations between DcR3 expression and Ki-67, PCNA LIs (r = 0.529, P < 0.01; r = 0.556, P < 0.01). The survival in the DcR3 negative group was 50 ± 1.79 months, longer than that of the DcR3 positive group (48.36 ± 2.90), however, without significance (P = 0.149). Different levels of DcR3 could also be detected in the culturing supernatants of all the 8 glioma cell lines and glioma cells freshly obtained from 8 human glioblastoma specimens. CONCLUSIONS: The overexpression of DcR3 might play a crucial role in the tumorigenesis, differentiation, and proliferation of glioma.

Activation of AKT is associated with metastasis of nasopharyngeal carcinoma.

Although radiotherapy results of nasopharyngeal carcinoma (NPC) at an early stage are better than other tumors, there is still a portion of patients with NPC who die before 5 years after the treatment; the underlying mechanism remains to be further understood. This study aims to investigate the mechanism by which NPC cells escape from irradiation. Patients with NPC at stage I was included in this study. All the patients were treated with irradiation. NPC biopsies were obtained from each patient before and 1 week after the start of radiotherapy. Expression of AKT in NPC tissue was assessed by Western blotting. NPC cell line, SUNE-1 cells, was treated with irradiation. The levels of AKT in SUNE-1 cells were also assessed. The frequency of apoptotic SUNE-1 cells was evaluated by flow cytometry. The levels of AKT were markedly increased in NPC tissue after treatment with irradiation, which was significantly correlated with NPC metastasis and mortality. After irradiation, NPC cell line, SUNE-1 cells, expressed higher levels of AKT than control cells. The knockdown of AKT in SUNE-1 cells markedly increased apoptotic cell rate. Radiotherapy can increase the levels of AKT in NPC cells that are associated with NPC metastasis and increase in mortality.

Intermittent hypoxia promotes hippocampal neurogenesis and produces antidepressant-like effects in adult rats.

Increasing evidence indicates that stimulating hippocampal neurogenesis could provide novel avenues for the treatment of depression, and recent studies have shown that in vitro neurogenesis is enhanced by hypoxia. The aim of this study was to investigate the potential regulatory capacity of an intermittent hypobaric hypoxia (IH) regimen on hippocampal neurogenesis and its possible antidepressant-like effect. Here, we show that IH promotes the proliferation of endogenous neuroprogenitors leading to more newborn neurons in hippocampus in adult rats. Importantly, IH produces antidepressant-like effects in multiple animal models screening for antidepressant activity, including the forced swimming test, chronic mild stress paradigm, and novelty-suppressed feeding test. Hippocampal x-ray irradiation blocked both the neurogenic and behavioral effects of IH, indicating that IH likely produces antidepressant-like effects via promoting neurogenesis in adult hippocampus. Furthermore, IH stably enhanced the expression of BDNF in hippocampus; both the antidepressant-like effect and the enhancement of cell proliferation induced by IH were totally blocked by pharmacological and biological inhibition of BDNF-TrkB (tyrosine receptor kinase B) signaling, suggesting that the neurogenic and antidepressant-like effects of IH may involve BDNF signaling. These observations might contribute to both a better understanding of physiological responses to IH and to developing IH as a novel therapeutic approach for depression.

Efficient inhibition of hepatitis B virus replication by hepatitis delta virus ribozymes delivered by targeting retrovirus.

BACKGROUND: Hepatitis delta virus (HDV) ribozyme is an attractive molecular tool that can specifically recognize and catalyze the self-cleavage of the viral RNA phosphodiester backbone. However, a major obstacle in the medical application of the HDV ribozyme is the lack of specificity in the delivery of the ribozyme to defined target cells. RESULTS: The objective of this study was to determine whether retroviral vectors can deliver the HDV ribozyme into the target cells and to elucidate whether HDV ribozyme plays a role in hepatitis B virus (HBV) replication. In our study, the transduction of helper-free pseudotyped retrovirus, which showed a broad host range, in human hepatoma cells was performed under 2 conditions, that is, in the presence of polymerized human serum albumin (pHSA) and in the absence of pHSA. The transduction ability in the presence of pHSA was higher than in the absence of pHSA. Moreover, HBsAg and HBeAg levels after transductions with pHSA were significantly lower than those in the absence of pHSA, thus indicating that the recombinant retrovirus had HBV-specific cleavage activity and targeted HepG2215 cells. CONCLUSIONS: These data suggest that this system provides a new approach for targeting hepatocytes and has a great potential in gene therapy for HBV infection.

18F-FDG PET/CT evaluation of lymphoma with renal involvement: comparison with renal carcinoma.

OBJECTIVE: Lymphoma can arise at any anatomic site, but it is rare to find kidney involvement. The aim of this study was to assess the role of F-flourodeoxyglucose (F-FDG) positron emission tomography (PET)/computed tomography (CT) in detecting lymphoma with renal involvement. Reports of such use of F-FDG PET/CT are limited. METHODS: Twelve lymphoma patients with renal involvement and 12 renal carcinoma patients were studied with F-FDG PET/CT. Intense F-FDG uptake, suggestive of positivity, was measured in mean standardized uptake values (standardized uptake values [SUV] mean). RESULTS: The results of PET/CT were validated by bone marrow, biopsy tissue and/or surgery. F-FDG PET/CT detected lymphoma with renal involvement lesions or renal carcinoma lesions in at least one site in the 24 patients. F-FDG uptake by the lymphoma lesions was much higher than the F-FDG uptake by the renal clear cell carcinomas (SUV mean 6.37 +/- 2.28 vs 2.58 +/- 0.62), and similar to that of renal cell carcinoma and renal collecting duct carcinoma (SUV mean 6.37 +/- 2.28 vs 6.27 +/- 1.15). There were dissimilar morphological changes in the homologous CT. Differing from renal cancer, lymphoma in the spleen, uterus, and bone marrow can easily be diagnosed by F-FDG PET/CT. CONCLUSION: The lesions of lymphoma with renal involvement, and especially those of primary renal lymphoma, are F-FDG avid. PET/CT appears to be useful in comparing these lesions with those of renal carcinoma, especially for primary renal lymphoma.

CREB and Sp1 regulate the human CD2AP gene promoter activity in renal tubular epithelial cells.

The human CD2-associated protein (CD2AP) is involved in several molecular signaling pathways and is an important factor responsible for nephrotic syndrome. Here we report the identification of the transcription start point and promoter region of the human CD2AP gene in renal tubular epithelial cells. With luciferase assays and deletion analysis, we found that the region between -558 and -1bp ahead of the transcription start point is indispensable for the promoter activity of the human CD2AP gene. A CREB site and two Sp1 sites were essential for maintaining the basal transcriptional activity of the human CD2AP promoter. Overexpression of phosphorylated CREB and Sp1 transactivated the human CD2AP promoter, whereas small interfering RNA-mediated blockage of CREB and Sp1 genes expressions inhibited markedly its activity. These findings provide the first analysis of the human CD2AP gene promoter and demonstrate that not only CREB but also Sp1 plays a critical role in regulating basal CD2AP promoter activity in renal tubular epithelial cells.

Camptothecin inhibits the progression of NPC by regulating TGF-ß-induced activation of the PI3K/AKT signaling pathway.

Nasopharyngeal carcinoma (NPC) is a type of cancer that is characterized by increased invasiveness, metastatic potential and tumor recurrence. Camptothecin has been demonstrated to exhibit anticancer activity. However, the potential underlying molecular mechanisms mediated by camptothecin in NPC cells remain elusive. In the present study, the efficacy of camptothecin for NPC was investigated in vitro and in vivo. Additionally, the potential signaling pathway mediated by camptothecin in NPC cells was also examined. The results indicated that the viability and aggressiveness of NPC cells were suppressed by camptothecin treatment in a dose-dependent manner. Camptothecin administration downregulated the expression levels of cell-cycle-associated proteins including cyclin 1, cyclin-dependent kinase (CDK)1 and CDK2 in NPC cells. Expression levels of migration-associated proteins including vimentin, fibronectin and epithelial cadherin were regulated by camptothecin treatment in NPC cells. Additionally, camptothecin inhibited the expression of transforming growth factor-ß (TGF-ß), phosphoinositide 3-kinase (PI3K) and protein kinase B (AKT), whereas TGF-ß overexpression abrogated camptothecin-mediated inhibition of PI3K and AKT expression and camptothecin-mediated inhibition of the viability and aggressiveness of NPC cells. Camptothecin significantly inhibited tumor growth and increased survival times in a mouse model of cancer. In conclusion, these results indicate that camptothecin treatment may inhibit the viability of NPC cells and aggressiveness by regulating the TGF-ß-induced PI3K/AKT signaling pathways, which in turn may be a potential molecular target for the treatment of NPC.

Reduced miR-433 expression is associated with advanced stages and early relapse of colorectal cancer and restored miR-433 expression suppresses the migration, invasion and proliferation of tumor cells in vitro and in nude mice.

The expression of microRNA (miR-433) is altered in various types of human cancer. The present study analyzed the prognostic and biological value of miR-433 expression in colorectal cancer using reverse transcription-quantitative polymerase chain reaction in 125 colorectal tissue specimens (including a test cohort of 40 cases of paired colorectal cancer and adjacent normal mucosae and a confirmation cohort of 85 cases of stage I-III colorectal cancer). In vitro and nude mouse xenograft experiments were subsequently used to assess the effects of miR-433 expression on the regulation of colorectal cancer cell proliferation, adhesion, migration, and invasion. The data indicated that miR-433 expression was significantly downregulated in colorectal cancer tissues in the test and confirmation patient cohorts and that low miR-433 expression was associated with advanced tumor stage and early relapse. Furthermore, the restoration of miR-433 expression was able to significantly inhibit the proliferation of tumor cells by inducing G1-S cell cycle arrest, suppressing cyclinD1 and CDK4 expression, and markedly inhibited the migratory and invasive capacities of tumor cells in vitro. The restoration of miR-433 expression or liposome-based delivery of miR-433 mimics suppressed the growth of colorectal cancer cell xenografts in nude mice. In conclusion, miR-433 may be a putative tumor suppressor in colorectal cancer, and the detection of low miR-433 expression will be investigated in further studies as a putative biomarker for the detection of early relapse in patients with colorectal cancer.

Influence of FDG-PET on computed tomography-based radiotherapy planning for locally recurrent nasopharyngeal carcinoma.

PURPOSE: Assuming F-18-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET)/computed tomography (CT) to be more accurate in representing the true disease extent than CT alone, we prospectively designed this study to evaluate how the addition of FDG-PET influences CT-based radiotherapy planning for locally recurrent nasopharyngeal carcinoma. PATIENTS AND METHODS: All patients underwent FDG-PET/CT simulation scans. For each patient, the gross tumor volume (GTV) was separately delineated with or without the addition of PET information and defined as GTV PET/CT and GTV CT, respectively. Corresponding planning target volumes (PTV) were generated for the GTV CT (PTV(CT)) and GTV PET/CT (PTV PET/CT). Three-dimensional conformal radiotherapy plans were separately created for PTV CT and PTV PET/CT. To assess the potential geographic miss of the PET/CT-based disease in CT-based treatment planning, the size and location of the GTV PET/CT, PTV(PET/CT), and PTV(CT) were analyzed, and the three-dimensional conformal radiotherapy plans created using the PTV CT were evaluated with the GTV PET/CT and PTV PET/CT information. RESULTS: A total of 43 patients were enrolled in this study. Distant metastasis was found in 4 patients with the addition of the PET information. The 39 patients without distant metastasis proceeded to three-dimensional conformal radiotherapy planning. Inadequate coverage of the GTV PET/CT and PTV PET/CT by the PTV CT occurred in 7 (18%) and 20 (51%) patients, respectively. This resulted in <95% of the GTV(PET/CT) and PTV PET/CT receiving >or=95% of the prescribed dose in 4 (10%) and 13 (33%) patients, respectively. CONCLUSIONS: The addition of FDG-PET information might influence CT-based radiotherapy planning for locally recurrent nasopharyngeal carcinoma by altering the definition of the target volume, with the potential to avoid a geographic miss of true disease.

Rna interference of annexin II gene in PC3 cells by using small interference RNA synthesized with in vitro transcription.

OBJECTIVE: To silence annexin II gene expression by using small interference RNA (siRNA) in prostate cancer cell line PC3. METHODS: 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. RESULTS: 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. CONCLUSIONS: The protocol for the synthesis of siRNA by T7 RNA polymerase is feasible. Annexin II might be involved in DNA synthesis.

Histone Methyltransferase SETDB1 Promotes the Progression of Colorectal Cancer by Inhibiting the Expression of TP53.

SETDB1 is a novel histone methyltransferase associated with the functional tri-methylation of histone H3K9. Although aberrant high expression of SETDB1 was experimentally obversed in a variety of solid tumors, its underlying mechanisms in human carcinogenesis are not well known. In this study, we investigated the expression of SETDB1 in a large cohort of colorectal cancer (CRC) samples and cell lines for the first time. Our findings showed that SETDB1 was highly expressed in majority CRC tissues and cell lines; moreover, up-regulation of SETDB1 was negatively correlated with the survival rate of CRC patients. Functionally, over-expression of SETDB1 significantly promoted the proliferation and migration of CRC cells in vitro and in vivo, while knocking down SETDB1 suppressed their growth. Mechanistically, we showed that over-expression of SETDB1 significantly inhibited the apoptosis induced by 5-Fluorouracil in CRC cells, which was closely related to the inhibition of TP53 and BAX expression. Furthermore, we confirmed that SETDB1 could be recruited to the promoter region of TP53, which might contribute its inhibition of apoptosis. For conclusion, our study indicated that SETDB1 is essential for colorectal carcinogenesis, and may be a newly target for treatment and prognostic evaluation in CRC.

Influence of [18F] fluorodeoxyglucose positron emission tomography on salvage treatment decision making for locally persistent nasopharyngeal carcinoma.

PURPOSE: The purpose of this study was to evaluate the role of [18F] fluorodeoxyglucose positron emission tomography (FDG-PET) in influencing salvage treatment decision making for locally persistent nasopharyngeal carcinoma (NPC). METHODS AND MATERIALS: A total of 33 NPC patients with histologic persistence at nasopharynx 1 to 6 weeks after a full course of radiotherapy underwent both computed tomography (CT) and FDG-PET/CT simulation at the same treatment position. The salvage treatment decisions, with regard to the decision to offer salvage treatment and the definition of gross tumor volume (GTV), were made before knowledge of the FDG-PET findings. Subsequently the salvage treatment decisions were made again based on the FDG-PET findings and compared with the pre-FDG-PET decisions. RESULTS: All 33 patients were referred for salvage treatment in the pre-FDG-PET decision. After knowledge of the FDG-PET results, the decision to offer salvage treatment was withdrawn in 4 of 33 patients (12.1%), as no abnormal uptake of FDG was found at nasopharynx. Spontaneous remission was observed in repeat biopsies and no local recurrence was found in these 4 cases. For the remaining 29 patients, GTV based on FDG-PET was smaller than GTV based on CT in 24 (82.8%) cases and was greater in 5 (17.2%) cases, respectively. The target volume had to be significantly modified in 9 of 29 patients (31%), as GTV based on FDG-PET images failed to be enclosed by the treated volume in the salvage treatment plan performed based on GTV based on CT simulation images. CONCLUSION: Use of FDG-PET was found to influence the salvage treatment decision making for locally persistent NPC by identifying patients who were not likely to benefit from additional treatment and by improving accuracy of GTV definition in salvage treatment planning.

[Effect of hypoxic radiosensitizer sodium glycididazole on long-term result of radiotherapy for nasopharyngeal carcinoma].

OBJECTIVE: To evaluate the long-term effect of sodium glycididazole (CMNa) as a hypoxic radiosensitizer on the radiotherapy for nasopharyngeal carcinoma. METHODS: Between May 1999 and May 2002, 211 patients with pathologically confirmed nasopharyngeal carcinoma were randomized into group-A treated by radiotherapy plus CMNa or group-B by radiotherapy alone. The staging was determined according to 92' Fuzhou staging systerm. The type, procession and dosage of radiotherapy were identical in both groups. The early adverse effect grade was assessed based on the CTC2.0 criteria and the late adverse effects were evaluated according to the RTOG/EORTC criteria. The median follow-up time was 52 months. All the data was analyzed by the SPSS 13.0 software. Characteristics and adverse events of these patients were compared between the two groups using t-test and the Wilcoxin rank sum test. Time-to-event curves were estimated using the Kaplan-Meier method. The prognostic parameters were analyzed using univariate analysis and the Cox multivariate regression analysis. RESULTS: The clinical data of the two groups were comparable. The 3-year survival was 88.4% in group-A, while 75.2% in group-B, with a statistically significant difference between two groups (P = 0.010). Univariate analysis showed that the 3-year survival was statistically correlated with N-staging ((N0-1, 86.9%, N2-3 73.8%, P < 0.001), T-staging (T1-2 85.6%, T3-4 79.3%, P = 0.014), TNM staging (P = 0.039), and whether using CMNa or not during rediotherapy (Group-A 88.4%, Group-B 75.2%, P = 0.010). The 5-year recurrence-free survival, 5-year metastasis-free survival and 5-year overall survival were 75.8%, 74.9% and 77.7% in Group-A, while 63.0%, 63.0% and 62.4% in Group-B with a statistically significant difference between two groups (0.013, 0.022 and 0.010, respectively). If stratified in the subgroups, the overall survival of stage III - IV patients was statistically different between group A and B (P = 0.009), however, not of stage I - II patients (P = 0.502). Cox multivariate regression analysis showed that the independent prognostic parameters for survival were N-stage (RR = 3.288) , T-stage (RR = 2.147) and use of CMNa during rediotherapy (RR = 0.407). However, there was no statistically significant difference between two groups in acute or late adverse effects on nervous system or heart, which suggested that use of CMNa during radiotherapy would not aggravate the toxicity caused by radiotherapy. CONCLUSION: Sodium glycididazole is well tolerable effective as a hypoxic radiosensitizer, which can improve the efficacy of radiotherapy and the long-term result of nasopharyngeal carcinom a patients, especially for the stage III - IV patients.

[miR-124 regulates radiosensitivity of colorectal cancer cells by targeting PRRX1].

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Dosimetric and clinical results of three-dimensional conformal radiotherapy for locally recurrent nasopharyngeal carcinoma.

PURPOSE: To assess the dosimetric and clinical results of three-dimensional conformal radiotherapy (3D CRT) for locally recurrent nasopharyngeal carcinoma (NPC). METHODS: A total of 86 patients with locally recurrent NPC were retreated with 3D CRT. The median prescribed dose was 68 Gy with 2 Gy per fractionation. Dosimetric quality was evaluated with dose distribution in planning target volume (PTV) and specified organs at risk (OAR), dose conformity index (CI) and dose homogeneity index (HI). The actuarial rate of local failure-free (LFF), overall survival (OS) and major late toxicities (MLT) were estimated with Kaplan-Meier method. Multivariate analysis for prognosis was performed using the Cox regression proportional hazards model. RESULTS: The mean dose to PTV averaged 66.8 Gy, and the dose to specified OAR was acceptable. The average value of CI and HI was 0.59 and 9.1%. The 5-year actuarial rate of LFF and OS was 71 and 40%, respectively. The 5-year actuarial incidence of MLT>or=Grade 3 and >or=Grade 4 were 100 and 49%, respectively. The major prognostic factors were T stage and the size of gross tumor volume (GTV). Advanced T stage and large GTV volume were associated with poor LFF and OS and high risk of MLT. CONCLUSION: The dosimetric quality of 3D CRT for locally recurrent NPC is generally excellent. A relatively high local control was achieved with this technique. However, the incidence of late toxicities were not found to decrease as originally expected. Early diagnosis of the recurrence and reasonable definition of the target volume are crucial to achieve a better outcome.

Antitumor effects and radiosensitization of cytosine deaminase and thymidine kinase fusion suicide gene on colorectal carcinoma cells.

AIM: To investigate the killing effect and radiosensitization of double suicide gene mediated by adenovirus on colorectal carcinoma cells. METHODS: Colorectal carcinoma cell line SW480 was transfected with adenovirus expression vector containing cytosine deaminase (CD) and thymidine kinase (TK) fusion gene. The expression of CD-TK fusion gene was detected by reverse transcriptase-polymerase chain reaction. The toxic effect of ganciclovir (GCV) and 5-fluorocytosine (5-FC) on infected cells was determined by MTT assay. The radiosensitization of double suicide gene was evaluated by clonogenic assay. RESULTS: After prodrugs were used, the survival rate of colorectal carcinoma cells was markedly decreased. When GCV and 5-FC were used in combination, the cytotoxicity and bystander effect were markedly superior to a single prodrug (chi2 = 30.371, P<0.01). Both GCV and 5-FC could sensitize colorectal carcinoma cells to the toxic effect of radiation, and greater radiosensitization was achieved when both prodrug were used in combination. CONCLUSION: CD-TK double suicide gene can kill and radiosensitize colorectal carcinoma cells.

Impact of prolonged fraction dose-delivery time modeling intensity-modulated radiation therapy on hepatocellular carcinoma cell killing.

AIM: To explore the impact of prolonged fraction dose-delivery time modeling intensity-modulated radiation therapy (IMRT) on cell killing of human hepatocellular carcinoma (HCC) HepG2 and Hep3B cell lines. METHODS: The radiobiological characteristics of human HCC HepG2 and Hep3b cell lines were studied with standard clonogenic assays, using standard linear-quadratic model and incomplete repair model to fit the dose-survival curves. The identical methods were also employed to investigate the biological effectiveness of irradiation protocols modeling clinical conventional fractionated external beam radiotherapy (EBRT, fraction delivery time 3 min) and IMRT with different prolonged fraction delivery time (15, 30, and 45 min). The differences of cell surviving fraction irradiated with different fraction delivery time were tested with paired t-test. Factors determining the impact of prolonged fraction delivery time on cell killing were analyzed. RESULTS: The alpha/ beta and repair half-time (T(1/2)) of HepG2 and Hep3b were 3.1 and 7.4 Gy, and 22 and 19 min respectively. The surviving fraction of HepG2 irradiated modeling IMRT with different fraction delivery time was significantly higher than irradiated modeling EBRT and the cell survival increased more pronouncedly with the fraction delivery time prolonged from 15 to 45 min, while no significant differences of cell survival in Hep3b were found between different fraction delivery time protocols. CONCLUSION: The prolonged fraction delivery time modeling IMRT significantly decreased the cell killing in HepG2 but not in Hep3b. The capability of sub-lethal damage repair was the predominant factor determining the cell killing decrease. These effects, if confirmed by clinical studies, should be considered in designing IMRT treatments for HCC.