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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An alteration of the p53 gene function is a major factor in the development of esophageal cancer. Recently, p53 gene therapy has been applied for clinical studies in lung cancer and head and neck cancer. However, no preclinical studies have yet demonstrated an anticancer effect of adenoviral-mediated wild-type p53 gene therapy on esophageal cancer. We herein evaluated the effect of p53 adenoviral gene therapy on human esophageal squamous cell carcinoma to test the ability of clinical application. A normal esophageal epithelial cell line (EN53F) and two human esophageal cancer cell lines (ECGI-10 and T.Tn) with a p53 alteration were used. The transduction efficiency, p53 protein expression, p21 protein expression, the induction of apoptosis, and growth suppression were assessed by using the recombinant adenoviral vector Ad5CMV-p53. The transduction efficiency was 60%-80% at 100 plaque-forming units (PFU)/cell and 80%-100% at 300PFU/cell. A significant growth suppression following an Ad5CMV-p53 infection was observed in both cancer cell lines. A Western blot analysis confirmed the presence of both exogenous p53 protein expression and p21 protein induction. Apoptotic cell death was observed with TUNEL staining. T.Tn xenografts in nude mice transduced with Ad5CMV-p53 demonstrated significant growth suppression. These data suggest that Ad5CMV-p53 may thus be a potentially effective therapeutic agent for locally advanced esophageal cancer.
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PMID:Preclinical study of adenoviral p53 gene therapy for esophageal cancer. 1149 54

Targeting the specific genetic lesions responsible for carcinogenesis and cancer progression is an attractive strategy for developing more effective anticancer therapies and reducing treatment-related toxicity. The restoration of defective tumor suppressor gene pathways by replacement of tumor suppressor genes in cancer cells has been studied in lung cancer. The most extensively studied agent is the wild-type p53 tumor suppressor gene delivered by an adenoviral vector. Clinical trials to date in non-small cell lung cancer and head and neck cancer have consistently shown evidence of gene transduction and expression, mediation of apoptosis, and clinical responses including pathologic complete responses. However, it also is clear that this approach can be improved. Promising avenues for investigation include improved gene delivery systems, induction of bystander effects, and adjuvant use of gene therapy with conventional chemotherapy, radiation therapy, and surgery. However, these strategies will need further refinement to succeed clinically. This review examines several important issues in cancer gene therapy in general and the most recent achievements in gene therapy for non-small cell lung cancer.
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PMID:Gene therapy approaches for the management of non-small cell lung cancer. 1160 84

The key roles of iron and iron proteins in cell proliferation make them potential targets for cancer therapy. However, clinical trials directed toward perturbation of tumor iron homeostasis by iron chelation have been limited to the use of deferoxamine (DFO). There is thus a need to develop agents with greater efficacy. In the present study, we investigated the mechanism of cytotoxicity of 311 (2-hydroxy-1-naphthylaldehyde benzoyl hydrazone), a novel iron chelator of the pyridoxal isonicotinoyl class. We found that 311 inhibited the growth of CCRF-CEM cells in a time- and concentration-dependent fashion with an IC(50) that was approximately 20-fold lower than that of DFO. 311 also inhibited the growth of breast, bladder, and head and neck cancer cell lines. Using electron spin resonance (ESR) spectroscopy analysis, we found that a 12-h exposure of CCRF-CEM cells to 311 inhibited the tyrosyl radical ESR signal of the R2 subunit of ribonucleotide reductase. However, overproduction of the R2 subunit in hydroxyurea-resistant CCRF-CEM cells was associated with a decrease in sensitivity of cells to 311 but not to DFO. Our studies show that 311 is a more potent cytotoxic agent than DFO, with activity against both hematopoietic and nonhematopoietic cell lines regardless of their p53 status. Furthermore, the ESR studies suggest that inhibition of the R2 subunit of ribonucleotide reductase is at least one mechanism by which 311 blocks cell proliferation.
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PMID:Inhibition of malignant cell growth by 311, a novel iron chelator of the pyridoxal isonicotinoyl hydrazone class: effect on the R2 subunit of ribonucleotide reductase. 1170 79

Cervical lymph node metastasis is the most common recurrence pattern of head and neck squamous cell carcinoma (HNSCC), and it is usually treated with radiation therapy and/or neck dissection. There has long been a desire for markers useful in predicting radiosensitivity to enable assignment of patients with recurrent head and neck cancer to clinical trials to improve their survival rates and quality of life. A total of 43 cases of HNSCC treated with whole or elective neck irradiation (total dose, 26-70 Gy; median, 60 Gy) for recurrent metastatic SCC in neck lymph nodes after neck dissection between 1992 and 1999 were the subject of this study. The relationship between radiosensitivity and clinicopathological and histopathological factors, including the Ki-67-labeling index for cell proliferation, p53 immunoreactivity and microvessel density (MVD), in surgical neck lymph node specimens were investigated by univariate and multivariate analysis. Of the 43 patients, 31 had recurrent tumors in neck lymph nodes after radiotherapy. Univariate analysis revealed significant associations between radiosensitivity and both high grade of keratinization (p=0.033) and low MVD (p=0.004), and marginally significant associations between radiosensitivity and grade of differentiation of the cancer in the lymph nodes (p=0.070). Multivariate analysis showed that only MVD had predictive value (p=0.016). Tumors with a high MVD possessed a significantly better neck control rate than tumors with a low MVD (p=0.004) by Kaplan-Meier analysis. MVD can be used as a good predictive marker for radiosensitivity of metastatic HNSCCs in cervical lymph nodes after neck dissection.
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PMID:Microvessel density predicts the radiosensitivity of metastatic head and neck squamous cell carcinoma in cervical lymph nodes. 1171 80

Previous studies have yielded inconsistent results on the prognostic significance of p53 and bcl-2 in head and neck cancer. The aim of this study was the evaluation of p53 and bcl-2 protein expression in laryngeal squamous cell carcinoma and to clarify the relationship between them. All patients with laryngeal carcinoma were treated during the period 1991-1993. In the present study p53 and bcl-2 expression in paraffin sections from 50 cases of laryngeal squamous cell carcinoma were analysed and correlated with routine clinico-pathological parameters. The expressions of p53 and bcl-2 were examined by immunohistochemical staining. Immunoreactivity for p53 was observed in 45 (90%) of carcinomas and bcl-2 immunoreactivity in 7 (14%). No significant correlation between the p53 or bcl-2 expression and patients' T- or N-stage, histological grading, or overall survival was found.
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PMID:Prognostic value of the expression of p53 and bcl-2 in patients with laryngeal carcinoma. 1182 92

Molecular therapy, including gene therapy, is a promising strategy for the treatment of human disease. However, delivery of molecular therapeutics efficiently and specifically to the target tissue remains a significant challenge. A human transferrin (Tf)-targeted cationic liposome-DNA complex, Tf-lipoplex, has shown high gene transfer efficiency and efficacy with human head and neck cancer in vitro and in vivo (Xu, L., Pirollo, K.F., Tang, W.H., Rait, A., and Chang, E.H. Hum. Gene Ther. 1999;10:2941-2952). Here we explore the structure, size, formation process, and structure-function relationships of Tf-lipoplex. We have observed Tf-lipoplex to have a highly compact structure, with a relatively uniform size of 50-90 nm. This nanostructure is novel in that it resembles a virus particle with a dense core enveloped by a membrane coated with Tf molecules spiking the surface. More importantly, compared with unliganded lipoplex, Tf-lipoplex shows enhanced stability, improved in vivo gene transfer efficiency, and long-term efficacy for systemic p53 gene therapy of human prostate cancer when used in combination with conventional radiotherapy. On the basis of our observations, we propose a multistep self-assembly process and Tf-facilitated DNA cocondensation model that may provide an explanation for the resultant small size and effectiveness of our nanostructural Tf-lipoplex system.
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PMID:Self-assembly of a virus-mimicking nanostructure system for efficient tumor-targeted gene delivery. 1186 Jul 13

Elevated levels of epidermal growth factor receptor in head and neck cancer have been extensively reported, and are correlated with poor prognosis. The combination of cisplatin and 5-fluorouracil is a standard treatment regimen for head and neck cancer, with radiation representing another therapeutic option. Six head and neck cancer cell lines were used to study the cytotoxic effects of combining ZD1839 ('Iressa'), a new selective epidermal growth factor receptor tyrosine kinase inhibitor, and radiation. Two of the cell lines were also used to study the combination of ZD1839 and cisplatin/5-fluorouracil. Cytotoxic effects were assessed by the MTT test. The results indicated that ZD1839 applied before radiation gave the best effects (P=0.002); an effect that was strongest in those p53-mutated cell lines that express the highest epidermal growth factor receptor levels. The effects of ZD1839 with cisplatin and/or 5-fluorouracil were sequence dependent (P<0.003), with the best results achieved when ZD1839 was applied first. For the triple combinations, ZD1839 applied before cisplatin and 5-fluorouracil resulted in a slight synergistic effect (P=0.03), although the effect was greater when ZD1839 was applied both before and during cytotoxic drug exposure. In conclusion, ZD1839 applied before radiation and before and/or during cisplatin/5-fluorouracil may improve the efficacy of treatment for head and neck cancer.
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PMID:Sequence-dependent effects of ZD1839 ('Iressa') in combination with cytotoxic treatment in human head and neck cancer. 1187 48

ONYX-015 (CI-1042), an adenovirus modified selectively to replicate in and kill cells that harbor p53 mutations, is under development by Onyx Pharmaceuticals for the potential treatment of various solid tumors, including head and neck, gastrointestinal and pancreatic tumors. It is a recombinant adenovirus that carries a loss-of-function mutation at the E1B locus, the product of which is a 55 kDa protein that binds to and inactivates the p53 tumor suppressor protein. Wild-type adenoviruses must disable this gene before viral replication can occur. This, the ONYX-015 adenovirus will leave normal cells unaffected. Mutations in the p53 tumor suppressor gene are the most common type of genetic abnormality in cancer, occurring in more than half of all major cancer types. Thus, these cells are susceptible to the virus, which will readily replicate and cause cell death. ONYX-015 is in ongoing phase III trials for the treatment of recurrent head and neck cancer, phase II trials for colorectal, ovary, pancreas and mouth tumors, and phase I trials for digestive disease, esophagus and liver tumors. Onyx Pharmaceuticals was granted US-05677178 covering methods for the treatment of p53-related cancers in October 1997. The patent specifically covers the use of modified adenoviruses and other DNA viruses, which lack viral proteins that bind to p53, for the treatment of cancer patients whose tumors lack p53 function. The USPTO awarded Onyx Pharmaceuticals US-05846945 in December 1998, covering methods for treating cancer using replicating adenoviral therapy in combination with chemotherapy. In April 1999, the company also received EP-094910177.8 covering the technology in Europe.
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PMID:ONYX-015. Onyx Pharmaceuticals. 1189 45

We have identified parameters which define a causal role of HPV16 in head and neck cancer. Twenty-eight tumours which were typed positive for HPV16 DNA, were comprehensively analysed for expression of the viral oncogenes E6 and E7, the status of the p53 gene, and the protein status of pRb and p16(INK4a). In a subset of cases, we have searched for integrated viral DNA, and have determined the genomic status of the E6 gene. Expression of E6/E7 was found in 12 tumours most of which were derived from the oropharynx, whereas p53 mutations were present in 13 tumours from various sites. The tumours either carried p53 mutations but did not express E6/E7, or they did express E6/E7 but were p53-wild-type. Coexistence of E6/E7 expression with a mutated p53 was found in only one case. Strikingly, in most p53-mutated tumours without E6/E7 expression, we found the E6 gene to be disrupted. E6/E7 expression was associated with reduced pRb and overexpressed p16(INK4a). Viral-cellular fusion transcripts were found in two cases. Our data demonstrate that HPV16 DNA-positivity in head and neck cancers is not indicative of a causal role. A causal role of HPV16 in head and neck cancer is defined by: E6/E7 expression, viral integration with an intact E6 gene, and perturbation of pRb cell cycle control. Mostly, the p53 gene is wild-type.
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PMID:Involvement of intact HPV16 E6/E7 gene expression in head and neck cancers with unaltered p53 status and perturbed pRb cell cycle control. 1189 79

Head and neck squamous cell carcinoma is a clinically challenging disease that resulted in more than 500,000 cases worldwide in 2001. In the United States, head and neck squamous cell carcinoma has accounted for approximately 40,000 cases with 12,000 deaths reported in 2001, which makes it the fifth leading cause of cancer incidence and the sixth leading cause of cancer-related deaths. Patients with recurrent or metastatic disease have a median survival rate of approximately 6 months; and there is little evidence from randomized trials that survival advantages have been achieved over the community standard of cisplatin and infusional 5-fluorouracil combination. Despite significant improvements in diagnosis, local management, and chemotherapy of head and neck cancer, there has been no significant increase in long-term survival rates over the past 30 years. As little progress has been made, new management approaches are required. Novel biologic agents have been developed to target multiple specific regions of the cancer cell. Epidermal growth factor receptor blockers have been investigated, such as anti epidermal growth factor receptor monoclonal antibodies, tyrosine kinase inhibitors, ligand conjugates, immunoconjugates, and antisense oligonucleotides. Farnesyl transferase inhibitors are a class of compounds that inhibit a critical enzymatic step in the constitutive expression of mutated ras genes, which are present in more than 27% of oral cancers. Strategies targeting the p53 gene and protein may halt or reverse the process of tumorigenesis and metastasis as p53 mutations occur in 45 to 70% of head and neck squamous cell carcinoma patients. Continued development of these novel agents may help improve the overall response and survival rate of patients with head and neck cancer.
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PMID:Novel therapeutics for head and neck cancer. 1198 Dec 81


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