Gene therapy for head and neck cancer

Efficacy of recombinant adenoviral human p53 gene in the treatment of lung cancer-mediated pleural effusion

Pleural effusion induced by lung cancer exerts a negative impact on quality of life and prognosis. The aim of the present study was to evaluate the value of the recombinant adenoviral human p53 gene (rAd-p53) in the local treatment of lung cancer and its synergistic effect with chemotherapy. The present study retrospectively recruited 210 patients with lung cancer-mediated pleural effusion who had adopted a treatment strategy of platinum chemotherapy. Pleurodesis was performed via the injection of cisplatin or rAd-p53. Long-term follow-up was conducted to investigate the therapeutic effects of cisplatin and rAd-p53 administration on pleural effusion and other relevant clinical indicators. The short-term effect of pleurodesis was as follows: The efficacy rate of rAd-p53 therapy was significantly higher compared with cisplatin therapy (71.26 vs. 54.47%), and the efficacy of treatment with ≥2×1012 viral particles of rAd-p53 for pleurodesis was significantly greater than treatment with 40 mg cisplatin (P<0.05). Furthermore, efficacy analysis performed 6 and 12 months after pleurodesis indicated that the efficacy rate of rAd-p53 was significantly greater than that of cisplatin (P<0.05). A comparison of median progression-free survival (PFS) time identified a significant difference (P<0.05) between rAd-p53 and cisplatin therapy (3.3 vs. 2.7 months); however, a comparison of median overall survival time identified no significant difference (P>0.05) between rAd-p53 and cisplatin therapy (9.6 vs. 8.7 months). In addition, Cox regression analysis indicated that PFS was not affected by clinical indicators such as age, gender, prognostic staging and smoking status; however, PFS was affected by pathological subtype (adenocarcinoma or squamous carcinoma) in the rAd-p53 group. rAd-p53 administration for pleurodesis exerts long-term therapeutic effects on the local treatment of lung cancer. Thus, a combination of rAd-p53 and chemotherapy may exert a synergistic effect and reverse multidrug resistance.

Expression of recombinant human adenovirus-p53 gene delivered into rabbit VX2 tumors by interventional methods

AIM: To investigate the expression of recombinant human adenovirus-p53 gene (rAd-p53, 1×10¹² VP) delivered into rabbit VX2 tumors by interventional methods.

METHODS: Thirty New Zealand rabbits were used to establish an animal model of hepatocarcinoma by implantation of the VX2 tumors into the liver. Eleven days after implantation, magnetic resonance imaging (MRI) and computed tomography (CT) scans were performed. Successful implantation was achieved in 27 rabbits. These rabbits were randomly divided into three groups: A, B and C. Groups A and B were infused through the hepatic artery with rAd-p53 (5 × 10⁶ VP) alone and rAd-p53 (5 × 10⁶ VP) plus lipiodol ultra fluid (0.5 mL), respectively, while group C was injected with rAd-p53 (5 × 10⁶ VP) into tumors by surgery. All model rabbits underwent digital subtraction angiography (DSA) during operation. The expression of P53, Bax and Bcl-2 proteins in tumor and peritumoral tissue was detected by immunohistochemistry at 24 and 72 hours and on 6 days after the operation.

RESULTS: MRI and CT scans showed that successful implantation was achieved in 27 rabbits, and the success rate was 95%. Immunohistochemical analysis indicated that P53, Bax and Bcl-2 proteins were expressed in all the three groups. The expression levels of P53 and Bax reached the peak at 72 hours. The expression levels of P53 and Bax in group C at 72 hours were significantly higher than those in groups A and B (P53: 70.3% ± 3.4% vs 62.4% ± 3.2% and 65.4% ± 2.1%; Bax: 43.7% ± 2.1% vs 35.7% ± 1.3% and 37.6% ± 2.4%, respectively; all P < 0.05). In contrast, the expression level of Bcl-2 in group C at 72 hours was significantly lower than those in groups A and B (12.0% ± 2.6% vs 18.0% ± 4.3% and 16.2% ± 3.1%, respectively; both P < 0.05).

CONCLUSION: P53 protein is expressed in rabbit VX2 tumors in a time-dependent manner. The expression level of P53 protein depends on the delivery methods used. The highest expression of P53 protein is achieved by intratumoral injection, followed by infusion of rAd-p53 plus lipiodol ultra fluid and rAd-p53 alone through the hepatic artery.

Cancer gene therapy using a novel secretable trimeric TRAIL

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), a member of the TNF family, is a type II transmembrane cytokine molecule. Soluble TRAIL has been shown to induce apoptosis in a wide variety of cancer cells in vitro and to suppress tumor growth specifically without damaging normal cells and tissues in vivo. In our previous report, we have demonstrated that an artificial gene encoding the polypeptide composed of the three functional elements (a secretion signal, a trimerization domain and an apoptosis-inducing moiety of TRAIL gene sequence) expresses and secretes highly apoptotic trimeric TRAIL into the culture supernatant. Here, as an approach to TRAIL-based cancer gene therapy, we developed an adenoviral vector delivering the gene that encodes our secretable trimeric TRAIL (stTRAIL). This adenovirus (Ad-stTRAIL) potently induced apoptosis in vitro in cancer cell lines such as HeLa, MDA-MB-231, A549, HCT116 and U-87MG. In an animal xenograft tumor model bearing a human glioma cell line U-87MG, intratumoral delivery of Ad-stTRAIL dramatically suppressed tumor growth without showing detectable adverse side effects. Histological analysis revealed that Ad-stTRAIL suppresses tumor growth by inducing apoptotic cell death. Contrary to the known rapid clearance of systemically delivered TRAIL protein from the blood circulation, stTRAIL expressed by Ad-stTRAIL in tumor tissues persisted for more than 4 days. In a comparison of tumor suppressor activity between Ad-stTRAIL and Ad-flTRAIL (delivering the full-length TRAIL gene) after mixing infected cells with uninfected cells and implanting these mixed cells in nude mice, Ad-stTRAIL showed higher tumor suppressor activity than that of Ad-flTRAIL. Our data reveal that a gene therapy using Ad-stTRAIL has a promising potential to treat human cancers including gliomas.

Adenovirus-mediated p53 gene therapy in pediatric soft-tissue sarcoma cell lines: sensitization to cisplatin and doxorubicin

Sarcomas, or tumors of connective tissue, represent roughly 20% of childhood cancers. Although the cure rate for sarcomas in general has significantly improved in the last 10 years, there continue to be subgroups that are difficult to treat. High-grade or metastatic soft-tissue sarcomas and rhabdomyosarcomas (RMS) of the extremities remain therapeutic challenges and their prognosis is often poor. The future of sarcoma therapy will likely include molecular approaches including gene/protein expression profiling and gene-based therapy. Most sarcomas harbor defects in the p53 or pRb pathways. The tumor suppressor p53 is central to regulation of cell growth and tumor suppression and restoring wild-type p53 function in pediatric sarcomas may be of therapeutic benefit. Studies with adenoviral-mediated p53 gene transfer have been conducted in many cancer types including cervical, ovarian, prostatic and head and neck tumors. Studies of this approach, however, remain limited in pediatric cancers, including sarcomas. Using three viral constructs containing cDNA for wild-type p53, mutant p53 (C135S) and lacZ, we studied the effect of adenoviral-mediated gene therapy in four pediatric sarcoma cell lines, RD and Rh4 (RMS), Rh1 (Ewing's sarcoma) and A204 (undifferentiated sarcoma). Using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay, we have shown a dose-dependent decrease in cell viability 72 h post-treatment that occurs with Ad-wtp53 but not with Ad-mutp53. Cells treated with Ad-wtp53 show upregulation of the p53 downstream targets, p21(CIP1/WAF1) and bax. Growth curves demonstrate suppression of cell growth over a period of 4 days and cells treated with Ad-wtp53 demonstrate a significant increase in sensitivity to the chemotherapeutic agents, cisplatin and doxorubicin. Our results indicate that restoration of wild-type p53 function in pediatric sarcoma cells could provide a basis for novel approaches to treatment of this disease.