E. coli NfsA: an alternative nitroreductase for prodrug activation gene therapy in combination with CB1954

Prodrug activation gene therapy is a developing approach to cancer treatment, whereby prodrug-activating enzymes are expressed in tumour cells. After administration of a non-toxic prodrug, its conversion to cytotoxic metabolites directly kills tumour cells expressing the activating enzyme, whereas the local spread of activated metabolites can kill nearby cells lacking the enzyme (bystander cell killing). One promising combination that has entered clinical trials uses the nitroreductase NfsB from Escherichia coli to activate the prodrug, CB1954, to a potent bifunctional alkylating agent. NfsA, the major E. coli nitroreductase, has greater activity with nitrofuran antibiotics, but it has not been compared in the past with NfsB for the activation of CB1954. We show superior in vitro kinetics of CB1954 activation by NfsA using the NADPH cofactor, and show that the expression of NfsA in bacterial or human cells results in a 3.5- to 8-fold greater sensitivity to CB1954, relative to NfsB. Although NfsB reduces either the 2-NO2 or 4-NO2 positions of CB1954 in an equimolar ratio, we show that NfsA preferentially reduces the 2-NO2 group, which leads to a greater bystander effect with cells expressing NfsA than with NfsB. NfsA is also more effective than NfsB for cell sensitisation to nitrofurans and to a selection of alternative, dinitrobenzamide mustard (DNBM) prodrugs

Establishment of a Transgenic Zebrafish Line for Superficial Skin Ablation and Functional Validation of Apoptosis Modulators In Vivo

BACKGROUND: Zebrafish skin is composed of enveloping and basal layers which form a first-line defense system against pathogens. Zebrafish epidermis contains ionocytes and mucous cells that aid secretion of acid/ions or mucous through skin. Previous studies demonstrated that fish skin is extremely sensitive to external stimuli. However, little is known about the molecular mechanisms that modulate skin cell apoptosis in zebrafish. METHODOLOGY/PRINCIPAL FINDINGS: This study aimed to create a platform to conduct conditional skin ablation and determine if it is possible to attenuate apoptotic stimuli by overexpressing potential apoptosis modulating genes in the skin of live animals. A transgenic zebrafish line of Tg(krt4:NTR-hKikGR)(cy17) (killer line), which can conditionally trigger apoptosis in superficial skin cells, was first established. When the killer line was incubated with the prodrug metrodinazole, the superficial skin displayed extensive apoptosis as judged by detection of massive TUNEL- and active caspase 3-positive signals. Great reductions in NTR-hKikGR(+) fluorescent signals accompanied epidermal cell apoptosis. This indicated that NTR-hKikGR(+) signal fluorescence can be utilized to evaluate apoptotic events in vivo. After removal of metrodinazole, the skin integrity progressively recovered and NTR-hKikGR(+) fluorescent signals gradually restored. In contrast, either crossing the killer line with testing lines or transiently injecting the killer line with testing vectors that expressed human constitutive active Akt1, mouse constitutive active Stat3, or HPV16 E6 element displayed apoptosis-resistant phenotypes to cytotoxic metrodinazole as judged by the loss of reduction in NTR-hKikGR(+) fluorescent signaling. CONCLUSION/SIGNIFICANCE: The killer/testing line binary system established in the current study demonstrates a nitroreductase/metrodinazole system that can be utilized to conditionally perform skin ablation in a real-time manner, and provides a valuable tool to visualize and quantify the anti-apoptotic potential of interesting target genes in vivo. The current work identifies a potential use for transgenic zebrafish as a high-throughput platform to validate potential apoptosis modulators in vivo

Upper aerodigestive tract cancer: summary of the National Institute for Health and Care Excellence guidelines for England and Wales.

The cancers of the upper aerodigestive tract (CUADT) considered in this guideline document include the oral cavity, oropharynx, nasopharynx, hypopharynx, larynx and paranasal sinus. Squamous cell carcinomas (SCC) are the predominant (91%) histological type of malignancies seen at these sites,with approximately 8500 people per annum being diagnosed with CUADT in England and Wales. This guideline deals with SCC and mucosal melanoma and applies to 94% of CUADT cancers. Between 1990 and 2006, the incidence of oropharyngeal cancer has doubled, oral cavity cancer showed a slight increase, whilst cases of larynx cancer have declined.1 Although the age and sex distribution varies across primary sites, SCCs are commoner in men with incidence starting at the age of 40, and peaking after the age of 60. The aetiologic factors associated with CUADT are smoking, alcohol, human papillomavirus (oropharynx only) and certain occupations.</p

Mucosal melanoma of the upper airways tract mucosal melanoma: A systematic review with meta-analyses of treatment.

Background Mucosal melanoma of the upper aerodigestive tract (MM-UADT) occurs in a complex anatomic region. It represents a small number of tumors of the head and neck and a small number of melanoma cases. Methods Search strategies initially identified 600, 11 of which were included in this study. Results All studies involved surgery and radiotherapy. None were randomized, and all were assessed as having a high risk of selection and performance bias. No studies reported quality of life, treatment-related mortality, or morbidity. The results indicate that the addition of radiotherapy to surgery reduces the rate of locoregional recurrence (hazard ratio [HR], 0.60; 95% confidence interval [CI], 0.42–0.87). There was no statistically significant difference in overall survival (HR, 1.16; 95% CI, 0.98–1.37). Conclusion Surgical resection with postoperative radiotherapy remains the optimal treatment strategy for locoregional control. More robust studies and the use of molecular targeted therapies need to be undertaken to improve overall survival.</p

Upper aerodigestive tract cancer: summary of the National Institute for Health and Care Excellence guidelines for England and Wales

The cancers of the upper aerodigestive tract (CUADT) considered in this guideline document include the oral cavity, oropharynx, nasopharynx, hypopharynx, larynx and paranasal sinus. Squamous cell carcinomas (SCC) are the predominant (91%) histological type of malignancies seen at these sites,with approximately 8500 people per annum being diagnosed with CUADT in England and Wales. This guideline deals with SCC and mucosal melanoma and applies to 94% of CUADT cancers. Between 1990 and 2006, the incidence of oropharyngeal cancer has doubled, oral cavity cancer showed a slight increase, whilst cases of larynx cancer have declined.1 Although the age and sex distribution varies across primary sites, SCCs are commoner in men with incidence starting at the age of 40, and peaking after the age of 60. The aetiologic factors associated with CUADT are smoking, alcohol, human papillomavirus (oropharynx only) and certain occupations.</p

Upper aerodigestive tract cancer: summary of the National Institute for Health and Care Excellence guidelines for England and Wales

The cancers of the upper aerodigestive tract (CUADT) considered in this guideline document include the oral cavity, oropharynx, nasopharynx, hypopharynx, larynx and paranasal sinus. Squamous cell carcinomas (SCC) are the predominant (91%) histological type of malignancies seen at these sites,with approximately 8500 people per annum being diagnosed with CUADT in England and Wales. This guideline deals with SCC and mucosal melanoma and applies to 94% of CUADT cancers. Between 1990 and 2006, the incidence of oropharyngeal cancer has doubled, oral cavity cancer showed a slight increase, whilst cases of larynx cancer have declined.1 Although the age and sex distribution varies across primary sites, SCCs are commoner in men with incidence starting at the age of 40, and peaking after the age of 60. The aetiologic factors associated with CUADT are smoking, alcohol, human papillomavirus (oropharynx only) and certain occupations.</p