Photoactivated Osmium Arene Anticancer Complexes.

Half-sandwich Os-arene complexes exhibit promising anticancer activity, but their photochemistry has hardly been explored. To exploit the photocytotoxicity and photochemistry of Os-arenes, O,O-chelated complexes [Os(η6-p-cymene)(Curc)Cl] (OsCUR-1, Curc = curcumin) and [Os(η6-biphenyl)(Curc)Cl] (OsCUR-2), and N,N-chelated complexes [Os(η6-biphenyl)(dpq)I]PF6 (OsDPQ-2, dpq = pyrazino[2,3-f][1,10]phenanthroline) and [Os(η6-biphenyl)(bpy)I]PF6 (OsBPY-2, bpy = 2,2'-bipyridine), have been investigated. The Os-arene curcumin complexes showed remarkable photocytotoxicity toward a range of cancer cell lines (blue light IC50: 2.6-5.8 µM, photocytotoxicity index PI = 23-34), especially toward cisplatin-resistant cancer cells, but were nontoxic to normal cells. They localized mainly in mitochondria in the dark but translocated to the nucleus upon photoirradiation, generating DNA and mitochondrial damage, which might contribute toward overcoming cisplatin resistance. Mitochondrial damage, apoptosis, ROS generation, DNA damage, angiogenesis inhibition, and colony formation were observed when A549 lung cancer cells were treated with OsCUR-2. The photochemistry of these Os-arene complexes was investigated by a combination of NMR, HPLC-MS, high energy resolution fluorescence detected (HERFD), X-ray adsorption near edge structure (XANES) spectroscopy, total fluorescence yield (TFY) XANES spectra, and theoretical computation. Selective photodissociation of the arene ligand and oxidation of Os(II) to Os(III) occurred under blue light or UVA excitation. This new approach to the design of novel Os-arene complexes as phototherapeutic agents suggests that the novel curcumin complex OsCUR-2, in particular, is a potential candidate for further development as a photosensitizer for anticancer photoactivated chemotherapy (PACT).

A double-regulated oncolytic adenovirus with improved safety for adenocarcinoma therapy.

Safety and efficiency are equally important to be considered in developing oncolytic adenovirus. Previously, we have reported that ZD55, an oncolytic adenovirus with the deletion of E1B-55K gene, exhibited potent antitumor activity. In this study, to improve the safety of ZD55, we utilized MUC1 promoter to replace the native promoter of E1A on the basis of ZD55, and generated a double-regulated adenovirus, named MUD55. Our data demonstrated that the expression of early and late genes of MUD55 was both reduced in MUC1-negative cells, resulting in its stricter glandular-tumor selective progeny production. The cytopathic effect of MUD55 was about 10-fold lower than mono-regulated adenovirus ZD55 or Ad.MUC1 in normal cells and not obviously attenuated in glandular tumor cells. Moreover, MUD55 showed the least liver toxicity when administrated by intravenous injection in nude mice. These results indicate that MUD55 could be a promising candidate for the treatment of adenocarcinoma.

Suppression of cancer growth in mice by adeno-associated virus vector-mediated IFN-beta expression driven by hTERT promoter.

Adeno-associated virus (AAV) has rapidly become a promising gene delivery vehicle for its excellent advantages of non-immunogenic, low pathogenicity and long-term gene expression in vivo. However, a major obstacle in development of effective AAV vector is the lack of tissue specificity, which caused low efficiency of AAV transfer to target cells. The application of human telomerase reverse transcriptase (hTERT) promoter is a prior targeting strategy for AAV in cancer gene therapy as hTERT activity is transcriptionally upregulated in most cancer cells. In the present work, we investigated whether AAV-mediated human interferon beta (IFN-beta) gene driven by hTERT promoter could specifically express in tumor cells and suppress tumor cell growth. Our data demonstrated that hTERT promoter-driven IFN-beta expression was the tumor-specific, decreased the cell viability of tumor cells but not normal cells, and induced tumor cell apoptosis via activation of caspase pathway and release of cytochrome c. AAV-mediated IFN-beta expression driven by hTERT promoter significantly suppressed the growth of colorectal cancer and lung cancer xenograft in mice and resulted in tumor cells death in vivo. These data suggested that AAVs in combination with hTERT-mediated IFN-beta expression could exert potential antitumor activity and provide a novel targeting approach to clinical gene therapy of varieties of cancers.

Significant antitumor activity of oncolytic adenovirus expressing human interferon-beta for hepatocellular carcinoma.

BACKGROUND: Human interferon-beta (IFN-beta) has been widely used in gene therapy for its antitumor activity but its therapeutic effect is limited. The conditionally replicative adenovirus ONYX-015 (a E1B-55-kDa-deleted adenovirus) targets well to tumor cells, but is not potent enough to cause significant tumor regression. To solve these problems, a tumor-selective replicating adenovirus expressing IFN-beta was constructed in this study. METHODS: The oncolytic adenoviruses were generated by homologous recombination in packaging cells. The expression of the IFN-beta protein was detected by enzyme-linked immunosorbent assay (ELISA). The antitumor efficacy of ZD55-IFN-beta was evaluated in cell lines and human hepatocellular carcinoma xenografts in nude mice. RESULTS: ZD55-IFN-beta can express much more IFN-beta than Ad-IFN-beta because of the replication of the ZD55 vector. Our data showed that ZD55-IFN-beta could exert a strong cytopathic effect on tumor cells (about 100-fold higher than Ad-IFN-beta or ONYX-015). Moreover, no obvious cytotoxic or apoptotic effects were detected in normal cells infected with ZD55-IFN-beta. CONCLUSIONS: The antitumor efficacy of IFN-beta could be significantly improved due to the increased gene expression level from the tumor-selective replicating vector. The oncolytic adenovirus expressing IFN-beta may provide a novel approach for cancer gene therapy.

Increased suppression of oncolytic adenovirus carrying mutant k5 on colorectal tumor.

Angiogenesis plays a key role in the development of a wide variety of malignant tumors. The approach of targeting antiangiogenesis has become an important field of cancer gene therapy. In this study, the antiangiogenesis protein K5 (the kringle 5 of human plasminogen) has been mutated by changing leucine71 to arginine to form mK5. Then the ZD55-mK5, which is an oncolytic adenovirus expressing mK5, was constructed. It showed stronger inhibition on proliferation of human umbilical vein endothelial cell. Moreover, in tube formation and embryonic chorioallantoic membrane assay, ZD55-mK5 exhibited more effective antiangiogenesis than ZD55-K5. In addition, ZD55-mK5 generated obvious suppression on the growth of colorectal tumor xenografts and prolonged the life span of nude mice. These results indicate that ZD55-mK5 is a potent agent for inhibiting the tumor angiogenesis and tumor growth.

[Meta analysis of clinical effectiveness of neoadjuvant chemotherapy for gastric cancer].

BACKGROUND & OBJECTIVE: Neoadjuvant chemotherapy has gained increasing attention as a treatment for gastric cancer since Wilke first reported its application to the treatment of gastric cancer in 1989. However, its value in treating gastric cancer remains controversial. This research was to assess the efficacy of neoadjuvant chemotherapy on gastric cancer through a Meta analysis of the randomized controlled trials published worldwide in both English and Chinese. METHODS: Cochrane systematic evaluation was used to search through Cochrane libraries of clinical comparative trials, PubMed, Embase, Chinese Biomedical Literature Database (CBM), Chinese Scientific Journal Full-text Database (CSJD) and Chinese Journal Full-text Database (CJFD), aided with manual retrieval and other retrievals. The quality of the assessment was independently evaluated and cross-checked by two evaluators, and the results of homogeneous studies were analyzed with RevMan4.2.10 software. RESULTS: Five randomized controlled trials involved a total of 838 patients were studied. Of the 5 trials, 2 were performed in Japan, 1 in the Netherlands, 1 in the United Kingdom, 1 in China. Of the 838 patients, 373 were treated with neoadjuvant chemotherapy and 465 were treated with surgery alone. Among the above 5 studies, one used blind method and one described random allocation concealment method. No statistical differences were found in the resection rate, cure rate, 1-and 5-year survival rates between neoadjuvant chemotherapy group and surgery group [odds ratio (OR)=1.09, 95% confidence interval (CI)=0.67-1.77 for resection rate; OR=1.25, 95% CI=0.85-1.84 for cure rate; OR=1.61, 95% CI=0.90-2.90 for 1-year survival rate; OR=1.13, 95% CI=0.83-1.53 for 5-year survival rate]. CONCLUSIONS: The efficacy of neoadjuvant chemotherapy on gastric cancer is not better than that of surgery alone. Therefore, neoadjuvant chemotherapy should not be recommended as a regular treatment for gastric cancer before obtaining evidences of its certain efficacy on gastric cancer.

Enhanced sensitivity to mitomycin C by abating heat shock protein 70 expression in human bladder cancer cell line of BIU-87.

BACKGROUND: Bladder cancer is a relatively common tumor in the urinary system, in which mitomycin C (MMC)-based chemotherapy or combination chemotherapy has been mainly used to treat patients with advanced bladder cancer. The prognosis of patients with advanced bladder cancer is still extremely poor in spite of recent therapeutic advances. To improve the prognosis, the sensitivity of tumor cells to mitomycin C by the induction of apoptosis with the abating heat shock protein 70 (HSP70) expression in human bladder cancer cell lines of BIU-87 was investigated. METHODS: HSP70 expression was abated in BIU-87 cells by HSP mRNA antisense oligomers. MTT assay and the clone-forming test were used for evaluating the sensitivity of cells to MMC. Apoptosis was assessed using both fluorescent microscopy after staining the cells with Hoechst 33258 and DNA fragment ladder agarose electrophoresis. Thirty-two male six-week-old BALB/c nude mice, at the beginning of the experiment, were used to evaluate the effect of antisense oligomers (ASO) on the tumor formation in vivo. RESULTS: HSP70 expression in BIU-87 was effectively abated by HSP70 mRNA antisense oligomers. The percentage of apoptotic cells in ASO group was greater than in sense oligomers (SO) [P < 0.05, (18.31 +/- 2.89)% vs (1.89 +/- 0.74)%], nonsense oligomers (NO) [P < 0.05, (18.31 +/- 2.89)% vs (1.78 +/- 0.92)%] and blank groups [P < 0.05, (18.31 +/- 2.89)% vs (1.87 +/- 0.84)%], while the sensitivity of tumor cells to mitomycin C was enhanced. The in vivo tumor inhibition rate of ASO plus MMC (> 50%) was more than that of ASO or MMC group alone (all P < 0.05). CONCLUSIONS: The abating level of HSP70 expression can strengthen the sensitivity of BIU-87 to MMC. One of this effect might be related to the induction of apoptosis by abating HSP70 expression.

[The significance of the expression of cyclooxygenase-2 in bladder transitional cell carcinoma tissues].

OBJECTIVE: To investigate the expression of cyclooxygenase-2 (COX-2) in bladder transitional cell carcinoma tissues, and understand its clinical significance. METHODS: Reversal transcription polymerase chain reaction (RT-PCR) was used to assess the expression of COX-2 mRNA in 52 cases of bladder transitional cell carcinoma tissues and 17 cases of normal bladder tissues far from neoplasm; Western blot was used to assess the expression of COX-2 protein in 49 cases of bladder cancerous tissues and 17 cases of normal tissues. RESULTS: Positive expression of COX-2 mRNA was detected in 83% (43/52) of bladder cancer tissues and in 29% (5/17) of normal tissues by RT-PCR and there was significant difference in expression of COX-2 mRNA between cancer tissues and normal tissues. Western blot analysis showed that expression of COX-2 protein was correlation with the stage and grade of cancer. CONCLUSION: COX-2 is overexpressed in bladder transitional cell carcinoma. COX-2 maybe play a certain role in carcinogenesis and progression of bladder cancer and turn into a useful target of chemoprevention of bladder cancer.

[The heat shock protein 70 antisense oligomers enhance the sensitivity of bladder cancer cell EJ to mitomycin C].

OBJECTIVE: To investigate whether the heat shock protein (HSP) 70 antisense oligomers can enhance the sensitivity of bladder cancer cell EJ to mitomycin C. METHODS: The HSP70 mRNA of EJ cells was blocked by the 10 micromol/L HSP70 antisense oligomers, while its effect on cell growth was evaluated by methyl thiazolyl tetrazolium (MTT) and colony forming ability test. RESULTS: The HSP70 expressions in HSP70 antisense treated group were lower than the corresponding sense and nonsense treated groups (P < 0.01). While, the increased sensitivity of EJ to mitomycin C was found in antisense treated group, compared with the corresponding sense and nonsense treated groups (P < 0.01). CONCLUSION: The sensitivity of bladder cancer cell EJ to mitomycin C was enhanced by the blockage of the HSP70 expression.