Fuxiang Zhou

Nasopharyngeal carcinoma risk by histologic type in central China: Impact of smoking, alcohol and family history

The role of cigarette smoking, alcohol use, family history of cancer and the interaction of cigarettes and family history in the etiology of Nasopharyngeal carcinoma (NPC) in general and within each histologic type are unclear. We conducted a case‐control study among 1,044 Han Chinese patients with NPC and 1,095 Han Chinese cancer‐free control subjects. Logistic regression was used to analyze the association between histologic type of NPC and cigarette smoking, alcohol drinking and family history. The results indicated that NPC was significantly associated with cigarette smoking [adjusted odds ratio (OR) = 2.97, 95% confidence interval (CI), 2.38–3.70], and the association exhibited a dose‐response relationship for intensity, duration, and cumulative consumption of cigarettes (ptrend < 0.0001 for intensity, duration and cumulative consumption of cigarettes). Positive family history of cancer led to a significant 12‐fold elevated risk of NPC (adjusted OR = 12.95, 95% CI, 7.12–23.54) and acted jointly with cigarettes in contributing to NPC risk (adjusted OR = 56.68, 95% CI, 17.25–186.19). The association of NPC risk with cigarettes was stronger for nonkeratinizing carcinoma than for keratinizing squamous cell carcinoma (KSCC), whereas family history was more closely associated with KSCC. NPC risk was not associated with alcohol consumption. Our study demonstrated that cigarette smoking and family history of cancer could serve independently and jointly as risk factors for etiology of NPC and might affect the risk of histology‐specific NPC differently. This knowledge may help facilitate comprehension of NPC etiology in general as well as within each histologic type, and thereby improve prevention efforts.

Novel, chimeric, cancer-specific, and radiation-inducible gene promoters for suicide gene therapy of cancer†

Although the promoter of the human telomerase reverse transcriptase (hTERT) gene has been widely used in gene therapy for targeted cancer cells, it has some limitations for clinical use because of its low activity and potential toxicity to certain normal cells. To overcome these defects, the authors generated novel chimeric hTERT promoters that contained the radiation‐inducible sequence CC(A/T)6GG (known as CArG elements).

Gene therapy with tumor-specific promoter mediated suicide gene plus IL-12 gene enhanced tumor inhibition and prolonged host survival in a murine model of Lewis lung carcinoma

BackgroundGene therapy is a promising therapeutic approach for cancer. Targeted expression of desired therapeutic proteins within the tumor is the best approach to reduce toxicity and improve survival. This study is to establish a more effective and less toxic gene therapy of cancer.MethodsCombined gene therapy strategy with recombinant adenovirus expressing horseradish peroxidase (HRP) mediated by human telomerase reverse transcriptase (hTERT) promoter (AdhTERTHRP) and murine interleukin-12 (mIL-12) under the control of Cytomegalovirus (CMV) promoter (AdCMVmIL-12) was developed and evaluated against Lewis lung carcinoma (LLC) both in vivo and in vitro. The mechanism of action and systemic toxicities were also investigated.ResultsThe combination of AdhTERTHRP/indole-3-acetic acid (IAA) treatment and AdCMVmIL-12 resulted in significant tumor growth inhibition and survival improvement compared with AdhTERTHRP/IAA alone (tumor volume, 427.4 ± 48.7 mm3vs 581.9 ± 46.9 mm3, p = 0.005 on day 15; median overall survival (OS), 51 d vs 33 d) or AdCMVmIL-12 alone (tumor volume, 362.2 ± 33.8 mm3vs 494.4 ± 70.2 mm3, p = 0.046 on day 12; median OS, 51 d vs 36 d). The combination treatment stimulated more CD4+ and CD8+ T lymphocyte infiltration in tumors, compared with either AdCMVmIL-12 alone (1.3-fold increase for CD4+ T cells and 1.2-fold increase for CD8+ T cells, P < 0.01) or AdhTERTHRP alone (2.1-fold increase for CD4+ T cells and 2.2-fold increase for CD8+ T cells, P < 0.01). The apoptotic cells in combination group were significantly increased in comparison with AdCMVmIL-12 alone group (2.8-fold increase, P < 0.01) or AdhTERTHRP alone group (1.6-fold increase, P < 0.01). No significant systematic toxicities were observed.ConclusionsCombination gene therapy with AdhTERTHRP/IAA and AdCMVmIL-12 could significantly inhibit tumor growth and improve host survival in LLC model, without significant systemic adverse effects.

Downregulation of high mobility group box 1 modulates telomere homeostasis and increases the radiosensitivity of human breast cancer cells

The functions of the high mobility group box 1 (HMGB1) in tumor cells include replenishing telomeric DNA and maintaining cell immortality. There is a negative correlation between human telomerase reverse transcriptase (hTERT) and radiosensitivity in tumor cells. Our aim was to elucidate the relationship among HMGB1, telomere homeostasis and radiosensitivity in MCF-7 cells. In this study, we established stably transfected control (MCF-7-NC) and HMGB1 knockdown (MCF-7-shHMGB1) cell lines. The expression of HMGB1 mRNA and the relative telomere length were examined by real-time PCR. Radiosensitivity was detected by clonogenic assay. The protein expressions were determined by western blot analysis. The telomerase activity was detected by PCR-ELISA. Proliferation ability was examined by CCK-8 assay. Cell cycle and apoptosis were examined by flow cytometry. DNA damage foci were detected by immunofluorescence. ShRNA-mediated downregulation of HMGB1 expression increased the radiosensitivity of MCF-7 cells, and reduced the accumulation of hTERT and cyclin D1. Moreover, knockdown of HMGB1 in MCF-7 cells inhibited telomerase activity and cell proliferation, while increasing the extent of apoptosis. Downregulation of HMGB1 modulated telomere homeostasis by changing the level of telomere-binding proteins, such as TPP1 (PTOP), TRF1 and TRF2. This downregulation also inhibited the ATM and ATR signaling pathways. The current data demonstrate that knockdown of HMGB1 breaks telomere homeostasis, enhances radiosensitivity, and suppresses the repair of DNA damage in human breast cancer cells. These results suggested that HMGB1 might be a potential radiotherapy target in human breast cancer.

ROCK Cooperated with ET-1 to Induce Epithelial to Mesenchymal Transition through SLUG in Human Ovarian Cancer Cells

The Rho-associated serine-threonine protein kinase (ROCK) is a downstream effector of Rho GTPases that is frequently activated in the epithelial to mesenchymal transition (EMT) of human ovarian cancer cells. On the other hand, endothelin-1 (ET-1) and its receptor endothelin A receptor (ETAR) are overexpressed in primary and metastatic ovarian carcinoma, which suggests that ET-1 promotes tumor dissemination. Hence, two human ovarian carcinoma cell lines, SK-OV-3 and CaOV3, were chosen to study the effects of ET-1/ETAR and ROCK in promoting EMT of ovarian cancer cells. We found that ET-1 exposure induced EMT of SK-OV-3 and CaOV3 by monitoring cells morphology, enhanced fibronectin, and reduced E-cadherin protein. At the same time, ET-1/ETAR enhanced the level of transcription of SLUG a transcriptional repressor of E-cadherin. More importantly, a constitutively active mutant of ROCK enhanced the transcription of SLUG by stimulating SLUG promoter activity. Furthermore, ROCK inhibitor Y27632 reversed the increase in fibronectin induced by ET-1/ETAR. Our data suggest that ROCK cooperated with ET-1/ETAR to promote EMT of human ovarian carcinoma cells through upregulation of SLUG mRNA.

Redistribution of DR4 and DR5 in lipid rafts accounts for the sensitivity to TRAIL in NSCLC cells.

The selective toxicity of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) against tumor cells makes it a potential targeted drug for treating non-small cell lung carcinomas (NSCLC). However, the majority of established human NSCLC cell lines are either partially or completely resistant to TRAIL, resulting in the limitation for clinical use of rhTRAIL and its agonistic antibodies. In this study, compared to TRAIL-sensitive H460 cell line, TRAIL-resistant A549 cell line showed a similar expression level of DR5 and a higer expression level of DR4. It indicates that there is no positive correlation between the expression levels of death receptors and sensitivity to TRAIL. However, tests on A549 cells with DR4 siRNA transfection revealed that DR4-competitive binding to TRAIL could not affect the capacity of TRAIL in inducing apoptosis. Instead, further studies found that the aggregation of DR4 and DR5 in lipid rafts only occured in H460 cells with TRAIL pretreatment. It suggested that the TRAIL-induced redistribution of DR4 and DR5 in lipid rafts contributed to the sensitivity to TRAIL in TRAIL-sensitive NSCLC H460 cell line, which was also confirmed by intervention tests of the cholesterol-sequestering agent nystatin.

Efficient inhibition of human telomerase activity by antisense oligonucleotides sensitizes cancer cells to radiotherapy

AbstractAim:To investigate the effect of the antisense oligonucleotides (ASODN) specific for human telomerase RNA (hTR) on radio sensitization and proliferation inhibition in human neurogliocytoma cells (U251).Methods:U251 cells were transfected with hTR ASODN or nonspecific oligonucleotides (NSODN). Before and after irradiation of 60Co-γ ray, telomerase activity was assayed by telomeric repeat amplification protocol (TRAP-PCR-ELISA), and DNA damage and repair were examined by the comet assay. The classical colony assay was used to plot the cell-survival curve, to detect the D0 value.Results:hTR antisense oligonucleotides could downregulate the telomerase activity, increase radiation induced DNA damage and reduce the subsequent repair. Furthermore, it could inhibit the proliferation and decrease the D0 value which demonstrates rising radiosensitivity. However, telomere length was unchanged over a short period of time.Conclusion:These findings suggest that an ASODN-based strategy may be used to develop telomerase inhibitors, which can efficiently sensitize radiotherapy.

Radiation enhances suicide gene therapy in radioresistant laryngeal squamous cell carcinoma via activation of a tumor-specific promoter

Radioresistant cells have been shown to correlate with poor outcome after radiotherapy. Here, we found that human telomerase reverse transcriptase promoter (hTERTp) had lower activity in laryngeal squamous carcinomas cells than in radioresistant variant cells. Combining radiotherapy with plasmid phTERTp-HRP, in which expression of enzyme horseradish peroxidase (HRP) controlled by hTERTp, resulted in increased apoptosis and necrosis of tumor cells after prodrug indole-3-acetic acid (IAA; converted by HRP into a cytotoxin) incubation. Volume and wet weight of xenograft tumor were reduced more in the combination groups. These data suggest that hTERTp has potential use in targeted cancer gene therapy, especially for radioresistant tumors. Combining radiotherapy with hTERTp-HRP/IAA may overcome radioresistance in laryngeal squamous carcinomas cells and amplify the killing effect in targeted cancer cells.

Telomere-Binding Protein TPP1 Modulates Telomere Homeostasis and Confers Radioresistance to Human Colorectal Cancer Cells

Background Radiotherapy is one of the major therapeutic strategies in cancer treatment. The telomere-binding protein TPP1 is an important component of the shelterin complex at mammalian telomeres. Our previous reports showed that TPP1 expression was elevated in radioresistant cells, but the exact effects and mechanisms of TPP1 on radiosensitivity is unclear. Principal Findings In this study, we found that elevated TPP1 expression significantly correlated with radioresistance and longer telomere length in human colorectal cancer cell lines. Moreover, TPP1 overexpression showed lengthened telomere length and a significant decrease of radiosensitivity to X-rays. TPP1 mediated radioresistance was correlated with a decreased apoptosis rate after IR exposure. Furthermore, TPP1 overexpression showed prolonged G2/M arrest mediated by ATM/ATR-Chk1 signal pathway after IR exposure. Moreover, TPP1 overexpression accelerated the repair kinetics of total DNA damage and telomere dysfunction induced by ionizing radiation. Conclusions We demonstrated that elevated expressions of TPP1 in human colorectal cancer cells could protect telomere from DNA damage and confer radioresistance. These results suggested that TPP1 may be a potential target in the radiotherapy of colorectal cancer.

Concomitant overexpression of EGFR and CXCR4 is associated with worse prognosis in a new molecular subtype of non-small cell lung cancer.

Although the relationships between CXCR4 and EGFR expression and survival in non‑small cell lung cancer (NSCLC) have been studied independently, dual CXCR4/EGFR tumor status and its relationship with survival has not been previously investigated. In the present study, we examined the relationship between CXCR4 expression, EGFR expression and dual CXCR4/EGFR expression and survival in patients with NSCLC (n=125) using immunohistochemical techniques. Overall survival was estimated using Kaplan-Meier and Cox proportional hazards models adjusting for patient age, tumor stage and type of treatments. Patients with CXCR4-positive tumors were significantly associated with distant metastasis and tended to have poorer prognosis compared to patients with CXCR4-negative tumors (HR=2.172, 95% CI=1.229‑3.839). No significant association between EGFR expression and survival was found; however co-expression of CXCR4/EGFR was a significant prognostic factor of worse overall survival (HR=2.741, 95% CI=1.330‑5.741). Furthermore, we showed that EGF enhanced the expression of CXCR4 in NSCLC cells through the PI-3K pathway, and treatment of NSCLC cells with EGFR phosphorylation inhibitor, AG1478, resulted in downregulation of the expression of CXCR4. These results suggest an important interaction between CXCR4 and EGFR intra-cellular pathways that may activate signals of tumor progression and may provide a valid explanation for the poor overall survival rate of patients whose co-expression of CXCR4 and EGFR is detected in tissue sections. Based on EGFR and CXCR4 expression, new molecular subtypes of NSCLC established in the present study can be used for customization of NSCLC treatment. Our results also showed that EGFR and CXCR4 are potential therapeutic targets for NSCLC and that simultaneous inhibition of EGFR and CXCR4 in NSCLC patients with concomitant expression of both CXCR4 and EGFR may be an effective treatment strategy.