Chemoprevention of Lung Carcinogenesis by Dietary Nicotinamide and Inhaled Budesonide.

Nicotinamide, the amide form of vitamin B3, and budesonide, a synthetic glucocorticoid used in the treatment of asthma, were evaluated to determine their individual and combinational chemopreventive efficacy on benzo(a)pyrene-induced lung tumors in female A/J mice. Nicotinamide fed at a dietary concentration of 0.75% significantly inhibited tumor multiplicity. Nicotinamide by aerosol inhalation at doses up to 15 mg/kg/day did not result in a statistically significant reduction in tumor multiplicity. Finally, dietary nicotinamide was administered with aerosol budesonide and tumor multiplicity reduced by 90% at 1 week and 49% at 8 weeks post last carcinogen dose. We conclude nicotinamide is an effective and safe agent for lung cancer dietary prevention at both early- and late-stage carcinogenesis and that efficacy is increased with aerosol budesonide. Combination chemoprevention with these agents is a well-tolerated and effective strategy which could be clinically advanced to human studies.

Effects of talactoferrin alpha on lung adenoma prevention in A/J mice June 2, 2016.

Talactoferrin alpha is a promising non-toxic solid tumor cancer agent that met with success in the treatment of early-stage lung cancer clinically in humans. It is well-tolerated, anddendritic cell-stimulation is a target. We tested the efficacy of this agent in a chemoprevention setting in A/J mice. All groups received benzo[a]pyrene (B[a]P) by oral gavage in three doses of 3 mg/kg body weight over the course of one week. Animals were then randomized into 5 groups of 24 mice per group based on weight. Experimental diets oftalactoferrin alpha (Agennix Inc., Indianapolis, IN), at 1.40% and 0.42% of the diet, were started one week or eight weeks after the last dose of B[a]P. Animals were continued on the feeding schedule, weighed weekly, and monitored for toxicity. The study was concluded 16 weeks after administration of B[a]P. The agent was well-tolerated for the duration of the experiment and there was no observable toxicity or weight change. The average number of adenomas per animal was 14.04 ± 0.93 (N=24) in the control group, 18.14 ± 1.45 (N=22) in the early low-dose group, 16.70 ± 1.30 (N=23) in the late low-dose group, 15.09 ± 1.41 (N=23) in the early high-dose group and 14.46 ± 1.21 (N=24) in the late high-dose group. We conclude talactoferrinalpha is well-tolerated. However, it did not inhibit carcinogenesis at a dose of 1.4% or 0.42% of the diet, which equates to human doses of 1.12 g/kg/day or 0.336 g/kg/day.

N-methylnitrosourea­induced carcinoma as a model for laryngeal carcinogenesis.

BACKGROUND: Preclinical animal models to study laryngeal cancer are nonexistent. The purpose of this study was to describe a novel mice laryngeal cancer model. METHODS: A total of 18 six-week-old A/J mice were used. Animals underwent microdirect laryngoscopy, superficial larynx scratching, and instillation of N-methyl-N-nitrosourea (MNU) at 2 different concentrations (15 µL and 30 µL) or dimethyl sulfoxide (DMSO) to the control group directly to the larynx. Mice received a total of 5 instillations of MNU or DMSO at 1-week intervals. Mice were euthanized at 20 and 30 weeks after the last intervention and laryngeal histology was analyzed. RESULTS: Laryngeal instillation of MNU caused a 60% cancer conversion in the study group. CONCLUSION: Our findings demonstrate the feasibility of developing a murine laryngeal carcinogenesis model using direct topical instillation of MNU. This is the first murine model of laryngeal cancer and has great potential for evaluating new agents for chemoprevention and treatment for laryngeal carcinoma.

Chitin or chitin-like glycans as targets for late-term cancer chemoprevention.

A consistent observation in studies of carcinogenesis is that some glycans are expressed differently in cancer cells than in normal cells. A well-known example is the aberrant ß1-6 N-acetyl-d-glucosamine branching associated with metastasis and poor prognosis in many cancers. This commentary proposes that, although not found in normal mammalian cells, a chitin (ß-1,4-linked N-acetyl-d-glucosamine) or a chitin-like polysaccharide (e.g., hyaluronan) may exist as a cancer-associated glycan, which can be targeted by the novel pyrimidine nucleotide derivative SP-1015 (designed as a chitin synthase inhibitor). Preliminary chemoprevention data of our group showed SP-1015 in the diet can inhibit benzo(a)pyrene-induced neoplasia in the forestomach of female A/J mice, and, of importance, this activity occurred at late stages in carcinogenesis. While no effect was seen in the murine lung, this may be due to the low bioavailability of the compound. A different route of administration (e.g. inhalation of an aerosol) may have potential to inhibit pulmonary carcinogenesis. We hypothesize that inhibitors of chitin or chitin-like glycan formation may be effective chemopreventive agents and suggest that further work is needed to study these novel targets for cancer prevention.

A method of producing carcinoma in upper aerodigestive tree and esophagus of the Syrian golden hamster using wounding and instillation of N-methylnitrosourea.

Details of a method for producing carcinoma of the aerodigestive tree of the Syrian golden hamster and the use of this model to evaluate putative agents for chemoprevention of these carcinomas are described. The method produces a majority of squamous carcinomas of the trachea and glottis that follow squamous metaplasia of respiratory epithelium. In addition, seen are adenocarcinomas arising in glands of the respiratory tree. Squamous carcinomas of the digestive epithelium arise in primary squamous epithelium. These tumors of digestive epithelium have a growth pattern that differs from that of the respiratory epithelium in that they grow and invade without filling the epithelial layer with tumor cells.

An Interlocker concept of carcinogenesis.

A critical feature in the sequence of events occurring during carcinogenesis is the development of irreversibility. The term "Interlocker" is used here to denote a mechanism by which irreversibility is brought about. The presentation focuses on conceptualizations of such processes. Two will be described below.

Pharmacokinetics of 5-fluorouracil in the hamster following inhalation delivery of lipid-coated nanoparticles.

The inhalation delivery of 5-fluorouracil (5-FU) in lipid-coated nanoparticles (LNPs) to hamsters was evaluated to determine the feasibility for use in lung cancer chemotherapy. The inhaled dose, 30 mg LNPs/kg body weight (1.5 mg/kg 5-FU), was delivered over an 8-min interval. Fluorescein isothiocyanate dextran (FITC-dextran) was included within the LNPs to provide an estimate of the particle concentration. The concentration of FITC-dextran and total 5-FU (released and LNP-associated) was determined as a function of time in the lung, trachea, larynx, esophagus, and serum. Concentrations of 5-FU and FITC-dextran were initially high in the trachea, larynx, and esophagus, and lower in the lung. Within 24 h, greater than 99% of the LNPs were cleared from the respiratory tract and total 5-FU concentrations mirrored the LNP concentration. An eight-compartment pharmacokinetic model was used to describe the observed trends in concentrations of LNPs and total 5-FU and to estimate the released 5-FU concentration in the above tissues. From this analysis, effective local targeting as well as sustained efficacious concentrations of 5-FU in the expected tumor sites were demonstrated.

Development of a respirable, sustained release microcarrier for 5-fluorouracil I: In vitro assessment of liposomes, microspheres, and lipid coated nanoparticles.

The release rate of 5-fluorouracil (5-FU) from liposomes, microspheres, and lipid-coated nanoparticles (LNPs) was determined by microdialysis to investigate their use as a respirable delivery system for adjuvant (postsurgery) therapy of lung cancer. 5-FU was incorporated into liposomes using thin film hydration and into microspheres and LNPs by spray drying. Primary particle size distributions were measured by dynamic light scattering. Liposomes released 5-FU in 4-10 h (k(1) = 0.44-2.31/h, first-order release model). Extruded vesicles with diameters less than one micron released 5-FU more quickly than nonextruded vesicles. With poly-(lactide) (PLA) and Poly-(lactide-co-glycolide) (PLGA) microspheres, slower release rates were observed (k(1) = 0.067-0.202/h). Increasing the lactide:glycolide ratio (50:50-100:0) resulted in a progressive decrease in the release rate of 5-FU. poly-(lactide-co-caprolactone) (PLCL) microspheres released 5-FU more rapidly compared to PLGA systems (k(1) = 0.254-0.259/h). LNPs formulated with polymeric core excipients had lower release rates compared to monomeric excipients (k(1) = 0.043-0.105/h vs. k(1) = 0.192-0.345/h). Changing the lipid chain length of the shell lipid components had a relatively minor effect (k(1) = 0.043-0.129/h). Overall, these systems yielded a wide range of delivery durations that may be suitable for use as an inhalation delivery system for adjuvant therapy of lung cancer.

Chemoprevention of cancer of the upper respiratory tract of the Syrian golden hamster by aerosol administration of difluoromethylornithine and 5-fluorouracil.

Research aimed at identifying effective chemopreventive compounds active against carcinogenesis of the upper respiratory tract (URT) has been largely unsuccessful. We are addressing this problem by efforts at agent identification and by using aerosol delivery. Two compounds, difluoromethylornithine (DFMO) and 5-fluorouracil (5-FU) were investigated. DFMO is an irreversible inhibitor of ornithine decarboxylase, an enzyme important in cell proliferation. It has been used widely by oral administration for chemoprevention. 5-FU is a pyrimidine analog used extensively as a chemotherapeutic agent. It is generally administered i.v. and can cause considerable toxicity. However, aerosol administration for therapy of lung cancer in humans has been reported to be without adverse effects (Tatsumura et al., Br J Cancer 1993;68:1146-9). The experimental model used herein entailed six intratracheal administrations of methylnitrosourea (MNU) to hamsters. Each of the test agents was started about 1 week after MNU and was continued for 29 weeks with DFMO. Infiltrating squamous cell carcinomas of the URT occurred in 92% of the controls and were reduced by 50% in animals receiving DFMO (P = 0.0001). The experiment with 5-FU was of shorter duration being terminated 20 weeks after MNU. Thirty percent of the controls had infiltrating carcinomas and were reduced by 60% in animals receiving 5-FU (P = 0.0274). Both compounds resulted in a significant increase in the percent of cancer-free animals. These two agents may have selected use in subjects at high risk of cancer of the URT.

Treatment and prevention of intraepithelial neoplasia: an important target for accelerated new agent development.

Precancer or intraepithelial neoplasia (IEN) is a noninvasive lesion that has genetic abnormalities, loss of cellular control functions, and some phenotypic characteristics of invasive cancer and that predicts for a substantial likelihood of developing invasive cancer. The AACR Task Force on the Treatment and Prevention of IEN has delineated the relationship between IEN and cancer risk as well as the clinical benefit that can be derived from reducing IEN burden. Although several effective endoscopic and surgical treatments for IEN have become standard medical practice, these interventions can confer morbidity and do not treat the entire epithelial field at risk. The incidence of many epithelial cancers is continuing to rise, the number of individuals at risk is increasing with the aging population, and the rapid advancement of imaging and molecular diagnostics is bringing to light precancers that were heretofore clinically silent. There is therefore an urgent need to rapidly develop new treatment and prevention agents for IEN. The AACR IEN Task Force recommends focusing on established precancers as the target for new agent development because of the close association between dysplasia and invasive cancer and because a convincing reduction in IEN burden provides patient benefit by reducing cancer risk and/or by decreasing the need for invasive interventions. The IEN Task Force proposes several clinical trial designs that provide practical and feasible approaches to the rapid development of new agents to treat and prevent precancer.