Systemic Bcl-2 antisense oligodeoxynucleotide in combination with cisplatin cures EBV+ nasopharyngeal carcinoma xenografts in SCID mice

Nasopharyngeal carcinoma (NPC) is causally linked to Epstein-Barr virus (EBV), and the EBV oncoprotein, latent membrane protein 1 (LMP-1), is expressed in the majority of NPCs. LMP-1 upregulates antiapoptotic genes, including bcl-2, and Bcl-2 protein is overexpressed in NPC. Given the antiapoptotic and chemoprotective effects of Bcl-2, it represents a rational therapeutic target in NPC. We have investigated the antitumor and chemosensitizing effects of the Bcl-2 antisense oligodeoxynucleotide G3139 (oblimersen, Genasense) in NPC. For these studies, we used the C666-1 line, a stably infected NPC-derived line that co-expresses LMP-1 and Bcl-2. We have shown that G3139 treatment of C666-1 in vitro caused sequence-dependent suppression of Bcl-2 protein, inhibition of cell growth and enhanced sensitivity to cisplatin (CDDP), as measured by increased antiproliferative and apoptotic effects. In vivo, G3139 treatment (25 mg/kg every 3 days x 5 doses) delayed engraftment and significantly inhibited growth of established C666-1 xenografts in SCID mice compared to control oligo-treated animals. However, G3139 alone did not prevent engraftment or cure established tumors in any animals. In contrast, G3139 treatment (25 mg/kg every 3 days x 5 starting on day 7) in combination with CDDP (8 mg/kg on day 14) completely abrogated tumor engraftment in 80% of animals compared to CDDP (0%) or CDDP + control oligo (0%). When treatment was delayed until tumor was established, G3139 in combination with CDDP significantly inhibited tumor growth compared to CDDP or CDDP + control oligo, and cured 69% animals with established tumors. No animals treated with G3139, CDDP or CDDP + control oligo were cured. Tumor burden and response to treatment correlated with EBV DNA load in serum, measured by real-time PCR. Western blots of tumor extracts obtained during oligo treatment showed that Bcl-2 levels were significantly decreased in G3139-treated animals. Our studies have demonstrated that the Bcl-2 antisense oligodeoxynucleotide, G3139, has proapoptotic effects in C666-1, and in combination with CDDP, is curative in C666-1 NPC xenograft tumors in vivo. The sequence-dependency of these effects is consistent with an antisense mechanism. These studies suggest that Bcl-2 may represent a biologically relevant target for the development of novel combinatorial therapies for NPC.     

5-氮杂胞苷增加鼻咽癌细胞株C666-1放射敏感度的实验

 目的 研究5-氮杂胞苷（5-azacytidine, 5-Aza）对人鼻咽癌细胞C666-1放射敏感度的影响及可能机制。方法 用不同浓度5-氮杂胞苷（0、500、1000、3000、5000 nmol/L）处理C666-1细胞,MTT法检测C666-1细胞增殖,流式细胞仪检测C666-1细胞周期,Western blot法检测细胞凋亡相关蛋白cleaved Caspase-3、cleaved PARP及DNA损伤相关蛋白γ-H2AX的表达。结果 5-氮杂胞苷随着药物浓度的增加,对C666-1细胞生长抑制作用增强。用1 000 nmol/L 5-氮杂胞苷处理鼻咽癌细胞进行放射增敏研究。鼻咽癌细胞C666-1接受单纯电离辐射时SF2（照射2 Gy时的细胞存活率）为48%,5-氮杂胞苷联合电离辐射时SF2降为31%,放射增敏比为1.37。5-氮杂胞苷能增加电离辐射诱导凋亡相关蛋白cleaved Caspase-3及cleaved PARP的表达。结论 5-氮杂胞苷增加鼻咽癌C666-1细胞对电离辐射的敏感度,可能的机制为5-氮杂胞苷能增加电离辐射诱导细胞凋亡。     

Imaging and modulating antisense microdistribution in solid human xenograft tumor models.

PURPOSE: The tumor microenvironment is complex and heterogeneous, populated by tortuous irregular vasculature, hypoxic cells, and necrotic regions. These factors can all contribute to the biodistribution difficulties encountered by most cancer therapeutic agents. Antisense oligodeoxynucleotides (ASO) are a class of therapeutics where limited information is available about their distribution within a solid tumor environment. EXPERIMENTAL DESIGN: To assess ASO distribution, a fluorescein-labeled phosphorothionated ASO based on the G3139 mismatch control was injected systemically (i.v.) into tumor-bearing severe combined immunodeficient mice. Hoechst 33342 was injected i.v. to visualize active vasculature. Unstained sections were imaged through tiled fluorescence stereomicroscopy and then quantitated using novel algorithms. Tumor sections from four human tumor models were examined (CaSki, DU-145, C666-1, and C15) for hypoxia, apoptosis/necrosis, and morphology. RESULTS: For all four tumors, ASO accumulated within regions of hypoxia, necrosis, and apoptosis. Scatter plots of ASO versus active vasculature generated for each individual tumor revealed a consistent pattern of distribution of the ASO within each model. In C666-1 xenografts, the slopes of these scatter plots were significantly reduced from 0.41 to 0.16 when pretreated with the antivascular agent ZD6126 48 h before ASO injection. This was accompanied by the formation of large disseminated necrotic regions in the tumor, along with a 13.1 mmHg reduction in interstitial fluid pressure. CONCLUSIONS: These data suggest the possibility that these algorithms might offer a generalizable and objective methodology to describe the distribution of molecular therapeutic agents within a tumor microenvironment and to quantitatively assess distribution changes in response to combination therapies.     

Radiation therapy and concurrent cisplatin in management of locoregionally advanced nasopharyngeal carcinomas

Radiation therapy in combination with chemotherapy in the management of locoregionally advanced nasopharyngeal carcinomas is evaluated in an attempt to improve locoregional response, reduce locoregional failure and reduce systemic failure. The current study was designed to investigate radiation therapy and concurrent cisplatin in this context. From 1992 through 1997, 70 patients with locoregionally advanced nasopharyngeal carcinomas were treated with radiation therapy and concurrent cisplatin. External beam radiation dose was 60 Gy for T1, T2 and T3 tumors, 70 Gy for T4 tumors and 70 Gy for metastatic cervical lymph nodes. An intracavitary brachytherapy boost (10 Gy) was applied for T1, T2 and T3 tumors. Cisplatin (30 mg/m2) was administered weekly during external beam radiation therapy. Locoregional complete response was achieved in 63 patients, locoregional failure was observed in 4 patients and systemic failure was observed in 15. N-stage predicted systemic failure. Overall survival, locoregional failure-free survival and systemic failure-free survival were 63%, 79% and 75%, respectively, at three years. Grade 3 acute skin toxicity was observed in 2 patients, Grade 3 acute mucous membrane toxicity was observed in 6 and Grade 3 acute hematological toxicity was observed in 2 patients. Despite improved locoregional response, reduced locoregional failure and improved survival with radiation therapy and concurrent cisplatin, systemic failure remains prevalent for locoregionally advanced nasopharyngeal carcinomas.     

PPARb/d Agonist GW501516 Inhibits Tumorigenesis and Promotes Apoptosis of the Undifferentiated Nasopharyngeal Carcinoma C666-1 Cells by Regulating miR-206

In previous investigations, we reported that peroxisome proliferator-activated receptor / (PPAR / ) activation by GW501516 inhibits proliferation and promotes apoptosis in the undifferentiated C666-1 nasopharyngeal carcinoma (NPC) cells by modulating caspase-dependent apoptotic pathway. In the present study, the mechanism by which GW501516 induces apoptosis was explored from the perspective of microRNA (miRNA) expression. Among the assayed miRNAs that were involved in regulating the expression of antiapoptotic protein Bcl-2, miR-206 was increased significantly and specifically by GW501516 in C666-1 cells at both the in vitro level and at the in vivo xenograft samples. The induction on miR-206 expression caused by GW501516 was capable of being antagonized by the PPAR / antagonist GSK3787 and AMPK antagonist dorsomorphin in C666-1 cells. GW501516’s suppression on the growth and apoptosis of C666-1 cells was found to be dependent on the presence of miR-206. miR-206 overexpression resulted in suppressed proliferation and colony formation ability, and further triggered increased apoptosis in C666-1 cells in a caspase-dependent manner. The expression of cleaved caspase 3 and caspase 9, and the ratio of Bax to Bcl-2 were elevated remarkably by miR-206. Consistent with the in vitro result, miR-206 was corroborated to suppress the ectopic NPC xenograft tumorigenesis that derived from the C666-1 cells in BALB/c nu/nu mice. Taken together, the current data demonstrated that miR-206 plays a critical role in the direct apoptosis-promoting effect induced by GW501516 in C666-1 cells. Furthermore, the emphasized tumor-suppressive role of miR-206 in the C666-1 cells indicates that it has the potential to provide a new therapeutic approach for the undifferentiated NPC.     

Prognostic value of Bcl-2 in invasive breast cancer receiving chemotherapy and endocrine therapy

Apoptosis induced by anticancer agents is a mechanism of treatment activity, overexpression of antiapoptotic genes could produce drug resistant tumors. We have demonstrated that the susceptibility of Bcl-2-negative tumors to a series of anticancer drugs was significantly higher than that of Bcl-2-positive tumors. The purpose of this study was to examine if negative Bcl-2 expression has treatment benefit in breast cancer patients received chemotherapy and endocrine treatment. A cohort of 147 Japanese women with invasive ductal carcinoma was studied. All the patients received postoperative adjuvant therapy consisting of combination chemotherapy with cyclophosphamide, epirubicin, and fluorouracil, and tamoxifen therapy. The expression of Bcl-2, estrogen receptor (ER) and MIB-1 was evaluated in breast cancer surgical specimens. Bcl-2 immunostaining was inversely correlated with increasing histologic grade (p=0.0095) and MIB-1 (p=0.0128). Furthermore, a positive correlation between Bcl-2 and ER was observed (p<0.0001). Unexpectedly, survival curves determined by the Kaplan-Meier method and univariate analysis demonstrated that Bcl-2-positivity was associated with favorable prognosis (p=0.0430). Cox proportional hazard model demonstrated that positive Bcl-2 expression still has favorable survival (p=0.0242) after consideration of other prognostic factors. Our results imply that Bcl-2 is a significant favorable prognostic factor for breast cancer with chemotherapy and endocrine therapy.     

Antiviral agent cidofovir decreases Epstein-Barr virus (EBV) oncoproteins and enhances the radiosensitivity in EBV-related malignancies

The Epstein-Barr virus (EBV) is involved in the carcinogenesis of several human cancers such as nasopharyngeal carcinoma (NPC) and Burkitt lymphoma (BL). Given the consistent role of EBV in transformation and maintenance of malignant phenotype, antiviral strategies provide an attractive approach to target EBV-expressing cells. In that aim, we have tested the Cidofovir, which is an acyclic nucleoside phosphonate analog known to exert an antiproliferative activity in some human virus-related tumors. Here, we show that Cidofovir induces a downregulation of the EBV oncoprotein LMP1 associated with a decrease of the antiapoptotic Bcl-2 and an increase of the proapoptotic Bax protein in Raji (BL) and C15 (NPC) cells. Using BL cell line BL2 B95-8 (BL2 infected with the B95.8 strain of EBV), we addressed the relation between EBV genome expression and modulation of viral oncoproteins by Cidofovir and/or ionizing radiation (IR). Cidofovir was able to significantly reduce LMP1 and EBNA2 mRNA and protein expression. This effect was associated with inhibition of proliferation, stimulation of apoptosis, and decrease of Bcl-2 expression in BL2 B95.8 cells. In addition, Cidofovir enhanced the radiation-induced apoptosis and the radiosensitivity through the proteolytic cleavage of death effectors caspase-9 and -3, which was specifically induced by combined treatment in EBV-positive cells compared to their negative counterparts. Furthermore, the combined treatment in nude mice led to a complete tumor remission without increasing toxicity in two human EBV-related cancer xenografts (Raji and C15). These results provide the basis for a novel anticancer strategy to enhance the therapeutic ratio of IR in EBV-related cancers.     

Potential roles of antisense therapy in the molecular targeting of genes involved in cancer (review)

Recent advances in antisense methods targeting genes involved in cell proliferation, angiogenesis, and apoptosis provide a potential anticancer effect alone as well as in combination with drugs, and antisense therapy may be useful in overcoming drug resistance and increasing survival in patients with advanced cancer including those with solid tumors. In particular, antisense to Bcl-2 comprises a most promising therapy and is being tested in combination with anticancer drugs in randomized phase III trials for chronic lymphocytic leukemia, multiple myeloma, and malignant melanoma. The targeting of apoptosis-related proteins is promising for enhancing the effect of cancer chemotherapy. The molecular mechanism by which anticancer drugs induce apoptosis has been identified as mitochondrial dysfunction mediated by the release of cytochrome c. Modulation of multiple antiapoptotic signaling pathways involving Bcl-2 and Akt, which are related to growth factor-stimulated signal transduction in cell survival, is essential for enhancement of the cytotoxic effect of anticancer drugs. Herein, we review the current status of antisense therapy and its potential for enhancing anticancer drug-induced apoptosis.     

Benzethonium chloride: a novel anticancer agent identified by using a cell-based small-molecule screen.

PURPOSE: This study aims to identify a novel therapeutic agent for head and neck cancer and to evaluate its antitumor efficacy. EXPERIMENTAL DESIGN: A cell-based and phenotype-driven high-throughput screening of approximately 2,400 biologically active or clinically used compounds was done using a tetrazolium-based assay on FaDu (hypopharyngeal squamous cancer) and NIH 3T3 (untransformed mouse embryonic fibroblast) cells, with secondary screening done on C666-1 (nasopharyngeal cancer) and GM05757 (primary normal human fibroblast) lines. The "hit" compound was assayed for efficacy in combination with standard therapeutics on a panel of human cancer cell lines. Furthermore, its mode of action (using transmission electron microscopy and flow cytometry) and its in vivo efficacy (using xenograft models) were evaluated. RESULTS: Benzethonium chloride was identified as a novel cancer-specific compound. For benzethonium (48-hour incubation), the dose required to reduce cell viability by 50% was 3.8 micromol/L in FaDu, 42.2 micromol/L in NIH 3T3, 5.3 micromol/L in C666-1, and 17.0 micromol/L in GM05757. In vitro, this compound did not interfere with the effects of cisplatin, 5-fluorouracil, or gamma-irradiation. Benzethonium chloride induced apoptosis and activated caspases after 12 hours. Loss of mitochondrial membrane potential (DeltaPsiM) preceded cytosolic Ca2+ increase and cell death. In vivo, benzethonium chloride ablated the tumor-forming ability of FaDu cells, delayed the growth of xenograft tumors, and combined additively with local tumor radiation therapy. Evaluation of benzethonium chloride on the National Cancer Institute/NIH Developmental Therapeutics Program 60 human cancer cell lines revealed broad-range antitumor activity. CONCLUSIONS: This high-throughput screening identified a novel antimicrobial compound with significant broad-spectrum anticancer activity.     

Potential efficacy of p16 gene therapy for EBV-positive nasopharyngeal carcinoma

The p16 cell cycle inhibitory gene is a potentially critical molecular abnormality in nasopharyngeal carcinoma (NPC). Its expression is silenced through either deletion or promoter methylation in the vast majority of NPC. This in turn is associated with absent or reduced protein expression, which has been previously demonstrated by our group to correlate with inferior clinical outcome. Therefore, we were interested in evaluating the potential of adenoviral mediated p16 gene therapy (adv.p16) in an EBV-positive NPC model (C666-1). We confirm that under basal conditions, p16 protein is undetectable in C666-1 cells, which, in turn, is associated with retention of retinoblastoma protein (pRb) expression. P16 expression was observed as early as 4 hr after infection of C666-1 cells with adv.p16 (10 pfu/cell) with no discernible perturbation in pRb for up to 24 hr. At 48 hr post-infection, p16 expression continued to increase, but at this point, pRb expression started to decline significantly. Cell viability decreased in a dose-dependent manner, down to 20% using 50 pfu/cell of adv.p16. The addition of radiation therapy (RT) administered 24 hr post-infection achieved only a slightly additive cytotoxicity. Adv.p16 therapy resulted in multiple mechanisms of cytotoxicity, including cell cycle arrest at the G0/G1 phase, induction of senescence, along with apoptosis. Ex vivo infection of C666-1 cells with adv.p16 (25 pfu/cell) with subsequent implantation into scid mice completely prevented tumor formation, followed for up to 51 days. Our study demonstrates the potential efficacy of adv.p16 gene therapy for NPC, mediated through multimodal mechanisms of cytotoxicity. Future evaluations will examine strategies to increase in vivo tumor transduction with a view towards future clinical applications.     

Minicircle-IFNgamma induces antiproliferative and antitumoral effects in human nasopharyngeal carcinoma.

PURPOSE: The aims of this work were to investigate the antitumor effect of IFNgamma gene transfer on human nasopharyngeal carcinoma (NPC) and to assess the potential of minicircle vector for antitumor gene therapy. EXPERIMENTAL DESIGN: We developed a recombinant minicircle vector carrying the human IFNgamma gene and evaluated the effects of minicircle-mediated IFNgamma gene transfer on NPC cell lines in vitro and on xenografts in vivo. RESULTS: Relative to p2PhiC31-IFNgamma, minicircle-mediated IFNgamma gene transfer in vitro resulted in 19- to 102-fold greater IFNgamma expression levels in transfected cells (293, NIH 3T3, CNE-1, CNE-2, and C666-1) and inhibited the growth of CNE-1, CNE-2, and C666-1 cells more efficiently, reducing relative growth rates to 7.1 +/- 1.6%, 2.7 +/- 1.0%, and 6.1 +/- 1.6%, respectively. Flow cytometry and caspase-3 activity assays suggested that the antiproliferative effects of IFNgamma gene transfer on NPC cell lines could be attributed to G(0)-G(1) arrest and apoptosis. Minicircle-mediated intratumoral IFNgamma expression in vivo was 11 to 14 times higher than p2PhiC31-IFNgamma in CNE-2- and C666-1-xenografted mice and lasted for 21 days. Compared with p2PhiC31-IFNgamma treatment, minicircle-IFNgamma treatment significantly increased survival and achieved inhibition rates of 77.5% and 83%, respectively. CONCLUSIONS: Our data indicate that IFNgamma gene transfer exerts antiproliferative effects on NPC cells in vitro and leads to a profound antitumor effect in vivo. Minicircle-IFNgamma is more efficient than corresponding conventional plasmids due to its capability of mediating long-lasting high levels of IFNgamma gene expression. Therefore, minicircle-mediated IFNgamma gene transfer is a promising novel approach in the treatment of NPC.     

EBV-miR-BART5-3p靶向p53对鼻咽癌细胞放射敏感性的影响

目的:研究爱泼斯坦-巴尔病毒（EBV）-miR-BART5-3p对鼻咽癌细胞放射敏感性的影响,并探讨其作用机制。方法:体外培养人EBV阳性鼻咽癌细胞（C666-1）和人鼻咽癌细胞（CNE-2Z）,将CNE-2Z组细胞设置为正常组,C666-1细胞随机分为对照组、EBV-miR-BART5-3p NC组、EBV-miR-BART5-3p mimics组和EBV-miR-BART5-3p inhibitor组。用实时荧光定量PCR（RT-qPCR）法检测各组细胞及EBV阴性鼻咽癌患者和EBV阳性鼻咽癌患者癌组织中EBV-miR-BART5-3p表达情况,噻唑蓝（MTT）法检测各组细胞存活率,平板克隆实验评估各组放疗敏感性变化情况,膜联蛋白V-异硫氰酸荧光素/碘化丙啶（Annexin V-FITC/PI）法检测各组细胞凋亡敏感性变化,蛋白免疫印迹分析法检测转染后各组细胞p53、Bcl-2相关X蛋白（Bax）、半胱天冬氨酸酶-3（caspase-3）和Bcl-2蛋白表达情况,双荧光素酶报告实验验证EBV-miR-BART5-3p与p53的靶向关系。结果:与EBV阴性组相比,EBV阳性组鼻咽癌组织中EBV-miR-BART5-3p表达水平显著升高（P＜0.05）。与正常组相比,对照组EBV-miR-BART5-3p表达、存活率、克隆数量和Bcl-2蛋白表达水平显著升高（P＜0.05）,凋亡率、p53、Bax和caspase-3蛋白表达水平显著降低（P＜0.05）。与对照组和EBV-miR-BART5-3p NC组相比,EBV-miR-BART5-3p mimics组EBV-miR-BART5-3p表达水平、存活率、克隆数量和Bcl-2蛋白表达水平显著升高（P＜0.05）,凋亡率、p53、Bax和caspase-3蛋白表达水平显著降低（P＜0.05）;与对照组和EBV-miR-BART5-3p NC组相比,EBV-miR-BART5-3p inhibitor组EBV-miR-BART5-3p表达水平、存活率、克隆数量和Bcl-2蛋白表达水平显著降低（P＜0.05）,凋亡率、p53、Bax和caspase-3蛋白表达水平显著升高（P＜0.05）。双荧光素酶报告实验结果显示,与TP53-3' UTR-WT+EBV-miR-BART5-3p NC组比较,TP53-3' UTR-WT+EBV-miR-BART5-3p inhibitor组荧光素酶活性降低（P＜0.05）。结论:下调EBV-miR-BART5-3p可能通过靶向促进p53蛋白表达,提高人EBV阳性鼻咽癌细胞的放射敏感性。     

Antiangiogenic gene therapy with soluble VEGF-receptors -1, -2 and -3 together with paclitaxel prolongs survival of mice with human ovarian carcinoma

We compared effects of antiangiogenic gene therapy with a combination of soluble sVEGFR-1, sVEGFR-2 and sVEGFR-3 to chemotherapy with carboplatin and paclitaxel and to antiangiogenic monoclonal anti-VEGF-antibody bevacizumab in an intraperitoneal ovarian cancer xenograft model in mice (n = 80). Gene therapy was also combined with chemotherapy. Therapy was initiated when sizable tumors were confirmed in magnetic resonance imaging (MRI). Adenovirus-mediated gene transfer was performed intravenously (2 × 109 pfu), while chemotherapy and monoclonal anti-VEGF-antibody were dosed intraperitoneally. The study groups were as follows: AdLacZ control (n = 21); combination of AdsVEGFR-1, -2 and -3 (n = 21); combination of AdsVEGFR-1, -2, -3 and paclitaxel (n = 9); bevacizumab (n = 14); paclitaxel (n = 9) and carboplatin (n = 5). Effectiveness was assessed by survival time and surrogate measures such as sequential MRI, immunohistochemistry, microvessel density and tumor growth. Antiangiogenic gene therapy combined with paclitaxel significantly prolonged the mean survival of mice (25 days) compared to the controls (15 days) and all other treatment groups (p = 0.001). Bevacizumab treatment did not have any significant effect on the survival. Tumors of the mice treated by gene therapy were significantly smaller than in the control group (p = 0.021). The mean vascular density and total vascular area were also significantly smaller in the tumors of the gene therapy group (p = 0.01). These results show potential of the antiangiogenic gene therapy to improve efficacy of chemotherapy with paclitaxel and support testing of this approach in a phase I clinical trial for the treatment of ovarian cancer.     

A pitfall in the survival benefit of adjuvant chemotherapy for node- and hormone receptor-positive patients with breast cancer: the paradoxical role of Bcl-2 oncoprotein (review)

The survival benefit of adjuvant chemotherapy in node-positive patients with breast cancer compared with surgery alone has been established. The survival benefit differs considerably between hormone receptor-positive and -negative patients, and it is believed that the effectiveness of adjuvant chemotherapy can be increased by hormonal therapy with tamoxifen. In the present review, we discuss the rationale behind the effectiveness of combination treatment with anticancer drugs and tamoxifen in terms of the paradoxical role of Bcl-2 in apoptosis in breast cancer. The survival benefit between receptor-positive and -negative patients was assessed using previous reports of randomized controlled studies for postoperative adjuvant chemotherapy in node-positive breast cancer. Tamoxifen induces the anti-apoptotic gene, Bcl-2, by its effect on estradiol (E2), via an E2-response element in the promotor region of Bcl-2. The efficicacy of chemoendocrine therapy was assessed in terms of the influence of tamoxifen on the effect of anticancer drugs. Adjuvant chemotherapy, including anthracycline and non-anthracycline based regimens, has an overall survival benefit in node-positive breast cancer, with a 23.5% reduction in the annual odds of recurrence and a 15% reduction in mortality (P<0.00001). A comparison of the reduction of the relative risk indicates that the survival benefit in receptor-negative patients is superior to that in receptor-positive patients by approximately 3-fold. Further, in contrast to receptor-negative patients, there is no additional benefit from paclitaxel over doxorubicin and cyclophosphamide (AC) in receptor-positive patients. The possible reasons that the chemotherapy benefit in receptor-positive patients is small and marginal are the following: i) concurrent treatment or pretreatment with tamoxifen can increase plasma E2 levels in premenopausal patients, thereby inducing Bcl-2 in residual cancer cells, which might decrease drug-sensitivity in combination with chemotherapy; ii) induction of Bcl-2 might be involved predominantly in the resistance to taxanes, the cytotoxic action of which targets Bcl-2. Co-treatment or pretreatment with tamoxifen for adjuvant therapy might decrease the efficacy of anticancer drugs, an effect that is mediated by induction of Bcl-2, especially in premenopausal patients with node-positive breast cancer. Treatment with anticancer drugs should be followed by treatment with tamoxifen to produce a survival benefit from combination therapy in receptor-positive patients.     

Induction of cell cycle arrest and apoptosis in human nasopharyngeal carcinoma cells by ZD6474, an inhibitor of VEGFR tyrosine kinase with additional activity against EGFR tyrosine kinase

ZD6474 is a vascular endothelial growth factor receptor (VEGFR) and epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor. The present study was undertaken to investigate the direct antiproliferative effect of ZD6474 on human nasopharyngeal carcinoma (NPC) in vitro and the antitumor activity on NPC xenografts in vivo. Results indicated that ZD6474 treatment inhibited EGFR phosphorylation and led to a dose- and time-dependent decrease in NPC cell (CNE-1, CNE-2 and C666-1) proliferation. Further investigation demonstrated G0/G1 cell cycle arrest in all 3 cell lines, which was associated with an upregulation of p21 and/or p27, and downregulation of CDK4, CDK6 and CDK2. ZD6474 treatment also induced apoptosis in CNE-1 and CNE-2 cells. The apoptosis mechanisms involved reduction of Bcl-2 and/or Bcl-XL, induction of Bak and/or Bax, and activation of caspases-3, -9 and/or -8. The in vivo antitumor activity was evaluated in CNE-2 and C666-1 xenografted nude mice. Administration of ZD6474 (25-100 mg/kg/day, once-daily, p.o.) produced a dose-dependent inhibition of tumor growth and prolonged survival in both models. This study suggests that ZD6474 exerts direct antiproliferative effects on NPC cell lines in vitro by inducing G0/G1 arrest and apoptosis, and potent antitumor effects on NPC xenografts in vivo. It indicates that ZD6474 may offer a new and effective treatment for human NPC.     

Radiation enhances the anti-tumor effects of vaccinia-p53 gene therapy in glioma

The overall goal of this study was to analyze the effect and mechanism of radiation in combination with vaccinia viruses (VV) carrying the p53 gene against glioma. Comparison of two alternative treatments of cultured C6 (p53(+)) and 9L (p53(-)) rat glioma cells showed significantly reduced survival for both cell lines, especially 9L, when radiation was applied prior to virus versus radiation alone. High p53 protein expression mediated by VV-TK-p53 was measured in infected cells. Single modality treatment of C6 cells with psoralen and UV (PUV)-inactivated VV-TK-p53 (PUV-VV-TK-53) or radiation significantly decreased survival compared with PUV-inactivated L-15 (PUV-L-15) control virus. However, no difference was observed between radiation and combination treatments of C6 cells. In contrast, radiation followed by PUV-VV-TK-53 resulted in dramatic reduction of 9L cell viability, compared to single modality treatment. Flow cytometry analysis of Annexin-V-stained 9L cells showed that radiation and PUV-VV-TK-53 caused a significant decrease in live cells (17.2%) as compared to other treatments and control (61.6-98.3%). Apoptosis was observed in 37.2% of cells, while the range was 0.7-7.8% in other treatment groups; maximal p53 level was measured on day 7 post-infection. In athymic mice bearing C6 tumors, VV-TK-53 plus radiation in both single and multiple therapies resulted in significantly smaller tumors by day 30 compared to the agents given only once. Immunohistochemical analysis of tumor sections demonstrated p53 protein expression over 20 days after VV-TK-53 treatment. Analysis of blood and spleen cells of mice given multiple combination treatments showed significant splenomegaly, leukocytosis, and increased DNA synthesis and response to mitogen. Multiple combination treatments were also associated with significantly elevated natural killer and B cells in the spleen. There were no overt toxicities, although depression in red blood cell and thrombocyte parameters was noted. Collectively, the data demonstrate that radiation significantly improves the efficacy of VV-mediated tumor suppressor p53 therapy and may be a promising strategy for glioma treatment. Furthermore, the results support the conclusion that the mechanisms underlying the enhanced anti-tumor effect of combination treatment include apoptosis/necrosis and upregulation of innate immune defenses.     

Inhibition of the tumor necrosis factor-alpha pathway is radioprotective for the lung.

PURPOSE: Radiation-induced lung toxicity limits the delivery of high-dose radiation to thoracic tumors. Here, we investigated the potential of inhibiting the tumor necrosis factor-alpha (TNF-alpha) pathway as a novel radioprotection strategy. EXPERIMENTAL DESIGN: Mouse lungs were irradiated with various doses and assessed at varying times for TNF-alpha production. Lung toxicity was measured by apoptosis and pulmonary function testing. TNF receptor 1 (TNFR1) inhibition, achieved by genetic knockout or antisense oligonucleotide (ASO) silencing, was tested for selective lung protection in a mouse lung metastasis model of colon cancer. RESULTS: Lung radiation induced local production of TNF-alpha by macrophages in BALB/c mice 3 to 24 hours after radiation (15 Gy). A similar maximal induction was found 1 week after the start of radiation when 15 Gy was divided into five daily fractions. Cell apoptosis in the lung, measured by terminal deoxyribonucleotide transferase-mediated nick-end labeling staining (mostly epithelial cells) and Western blot for caspase-3, was induced by radiation in a dose- and time-dependent manner. Specific ASO inhibited lung TNFR1 expression and reduced radiation-induced apoptosis. Radiation decreased lung function in BALB/c and C57BL mice 4 to 8 weeks after completion of fractionated radiation (40 Gy). Inhibition of TNFR1 by genetic deficiency (C57BL mice) or therapeutic silencing with ASO (BALB/c mice) tended to preserve lung function without compromising lung tumor sensitivity to radiation. CONCLUSION: Radiation-induced lung TNF-alpha production correlates with early cell apoptosis and latent lung function damage. Inhibition of lung TNFR1 is selectively radioprotective for the lung without compromising tumor response. These findings support the development of a novel radioprotection strategy using inhibition of the TNF-alpha pathway.     

Cisplatin chemotherapy plus adenoviral p53 gene therapy in EBV-positive and -negative nasopharyngeal carcinoma

We have previously shown that the introduction of human recombinant wild-type p53 mediated by an adenoviral vector (Ad5CMV-p53), either alone or delivered in combination with ionizing radiation, was cytotoxic to two nasopharyngeal carcinoma (NPC) cell lines. To further explore the potential therapeutic role for gene therapy, the combination of Ad5CMV-p53 and cisplatin was examined in two NPC cell lines, CNE-1 and C666-1. The C666-1 cells are particularly relevant because they express Epstein-Barr virus latent gene products analogous to human NPC in situ. Cells were infected with 5 pfu/cell of Ad5CMV-p53 or Ad5CMV-beta-gal, followed by exposure to increasing doses of cisplatin. Clonogenic and MTT assays were used to assess the sensitivity of cells to these treatments, and apoptosis was also quantified. The combination of Ad5CMV-p53 and cisplatin resulted in approximately 25% greater cytotoxicity compared to that observed with cisplatin alone in either cell line. Apoptosis was induced in approximately 50% of cells following administration of both Ad5CMV-p53 and cisplatin, but was induced in considerably fewer cells following either treatment alone. The two modalities appeared to interact in an additive manner. Ad5CMV-p53 gene therapy resulted in the expression of biologically active p53 protein, shown by induction of p21(WAF1/CIP1). Cisplatin treatment showed little effect on either p53 or p21(WAF1/CIP1) expression. Therefore, both p53 gene therapy and cisplatin chemotherapy demonstrated cytotoxicity mediated by apoptosis despite the presence of EBV gene products in the C666-1 cells, but it appears that the two modalities induce cytotoxicity by independent pathways.     

Endostar, a recombined humanized endostatin, enhances the radioresponse for human nasopharyngeal carcinoma and human lung adenocarcinoma xenografts in mice

The purpose of this paper is to determine the efficacy of combining radiation therapy with endostar, a recombined humanized endostatin, in human nasopharyngeal carcinoma and human lung adenocarcinoma xenografts. Tumor xenografts were established in the hind limb of male athymic nude mice (BALB/c-nu) by subcutaneous transplantation. The tumor-bearing mice were assigned into four treatment groups: sham therapy (control), endostar (20 mg/kg, once daily for 10 days), radiation therapy (6 Gray per day to 30 Gray, once a day for 1 week), and endostar plus radiation therapy (combination). The experiment was repeated and mice were killed at days 3, 6, and 10 after initiation therapy, and the tumor tissues and blood samples were collected to analyze the kinetics of antitumor, antiangiogenesis, and antivascularization responses of different therapies. In human nasopharyngeal carcinoma and human lung adenocarcinoma xenografts, endostar significantly enhanced the effects of tumor growth inhibition, endothelial cell and tumor cell apoptosis induction, and improved tumor cell hypoxia of radiation therapy. Histological analyses demonstrated that endostar plus radiation also induced a significant reduction in microvascular density, microvascular area, and vascular endothelial growth factor and matrix metalloproteinase-2 expression compared with radiation and endostar alone respectively. We concluded that endostar significantly sensitized the function of radiation in antitumor and antiangiogenesis in human nasopharyngeal carcinoma and human lung adenocarcinoma xenografts by increasing the apoptosis of the endothelial cell and tumor cell, improving the hypoxia of the tumor cell, and changing the proangiogenic factors. These data provided a rational basis for clinical practice of this multimodality therapy. ( Cancer Sci 2009)