Establishment of a bioassay model for lung cancer chemoprevention initiated with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in female A/J mice

Relationship between Lung Carcinogenesis and Chronic Inflammation in Rodents

Simple Summary

Lung cancer is the most common cause of cancer-related deaths worldwide. There are various risk factors for lung cancer, including tobacco smoking, inhalation of dust particles, chronic inflammation, and genetic factors. Chronic inflammation has been considered a key factor that promotes tumor progression via production of cytokines, chemokines, cytotoxic mediators, and reactive oxygen species by inflammatory cells. Here, we review rodent models of lung tumor induced by tobacco, tobacco-related products, and pro-inflammatory materials as well as genetic modifications, and discuss the relationship between chronic inflammation and lung tumor. Through this review, we hope to clarify the effects of chronic inflammation on lung carcinogenesis and help develop new treatments for lung cancer.

Abstract

Lung cancer remains the leading cause of cancer-related deaths, with an estimated 1.76 million deaths reported in 2018. Numerous studies have focused on the prevention and treatment of lung cancer using rodent models. Various chemicals, including tobacco-derived agents induce lung cancer and pre-cancerous lesions in rodents. In recent years, transgenic engineered rodents, in particular, those generated with a focus on the well-known gene mutations in human lung cancer (KRAS, EGFR, and p53 mutations) have been widely studied. Animal studies have revealed that chronic inflammation significantly enhances lung carcinogenesis, and inhibition of inflammation suppresses cancer progression. Moreover, the reduction in tumor size by suppression of inflammation in animal experiments suggests that chronic inflammation influences the promotion of tumorigenesis. Here, we review rodent lung tumor models induced by various chemical carcinogens, including tobacco-related carcinogens, and transgenics, and discuss the roles of chronic inflammation in lung carcinogenesis.

Lung proliferative lesion-promoting effects of left pulmonary ligation in A/J female mice

This present study was conducted in an attempt to examine proliferative lesion‐promoting effect in the lung by compensatory lung growth after left pulmonary ligation. To examine a strong proliferative lesion‐promoting effect in the lung, the effects of left pulmonary ligation on lung proliferative lesions induced by 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanone (NNK) were examined for 12 weeks. The number of proliferative lesions induced by NNK in the right lung after left pulmonary ligation increased significantly after 12 weeks, indicated by an increase in the weight of the right lung. In addition, several messenger RNA (mRNA) markers, including insulin growth factor 1, were highly expressed in the right lung on the seventh day after left ligation. These experiments demonstrated the clear proliferative lesion‐promoting effects of pulmonary ligation on the induction of the expression of mRNAs related to the cell cycle, cell division and mitosis. However, the proliferative lesion‐promoting effects were not strong enough to allow a shortened experimental period for the establishment of the lung bioassay model. The results also indicated the necessity to pay attention to the possibility of a recurrence of lung cancer in the residual lung after resection in humans.

Effects of the expectorant drug ambroxol hydrochloride on chemically induced lung inflammatory and neoplastic lesions in rodents

Ambroxol hydrochloride (AH) is an expectorant drug used to stimulate pulmonary surfactant and serous airway secretion. Surfactant proteins (SPs) are essential for maintaining respiratory structure and function, although SP expression has also been reported in lung inflammatory and proliferative lesions. To determine whether AH exerts modulatory effects on these lung lesions, we examined its effects on pleural thickening induced by intrathoracic administration of dipotassium titanate (TISMO) in A/JJmsSlc (A/J) mice. We also analyzed the modulatory effects of AH on neoplastic lung lesions induced by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in A/J mice and by N-nitrosobis (2-hydroxypropyl) amine (DHPN) in F344/DuCrlCrj (F344) rats. A/J mice treated with TISMO showed decreased body weight, increased white blood cell (WBC) counts, and pleural thickening caused by pleuritis and poor general condition. However, A/J mice treated with TISMO + 120 ppm showed significant recovery of body weight and WBC counts to the same levels as those of A/J mice not treated with TISMO, although no significant differences were observed in histopathological changes including the immunohistopathological expression of IL-1β in the lung and maximum pleural thickness regardless of AH treatment. In the NNK and DHPN experiments, no significant differences in body weight, hematology, plasma biochemistry, and histopathological changes were associated with AH concentration. These results suggest that AH potentially exerts anti-inflammatory effects but does not have a direct suppressive effect on lung tumorigenesis in rodents.

Suppression of Tobacco Carcinogen-Induced Lung Tumorigenesis by Aerosol-Delivered Glycerol Propoxylate Triacrylate-Spermine Copolymer/Short Hairpin Rab25 RNA Complexes in Female A/J Mice

BACKGROUND

Rab25, a member of Rab family of small guanosine triphosphatase, is associated with progression of various types of human cancers, including lung cancer, the leading cause of cancer-associated deaths around the globe.

METHODS

In this study, we report the gene therapeutic effect of short hairpin Rab25 RNA (shRab25) on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in female A/J mice. Initially, mice (6 weeks old) were injected with single dose of NNK (2 mg/0.1 mL saline/mouse) by intraperitoneal injection to induce the tumor. Eight weeks later, shRab25 was complexed with glycerol propoxylate triacrylate-spermine (GPT-SPE) copolymer and delivered into tobacco-induced lung cancer models through a nose-only inhalation system twice a week for 2 months.

RESULTS

GPT-SPE/shRab25 largely decreased the tobacco-induced tumor numbers and tumor volume in the lungs compared to GPT-SPE- or GPT-SPE/shScr-delivered groups. Remarkably, aerosol-delivered GPT-SPE/shRab25 significantly decreased the expression level of Rab25 and other prominent apoptosis-related proteins in female A/J mice. The apoptosis in these mice was determined by detecting the expression level of Bcl-2, proliferating cell nuclear antigen, Bax, and further confirmed by TUNEL assay.

CONCLUSIONS

Our results strongly confirm the tumorigenic role of Rab25 in tobacco carcinogen-induced lung cancer and hence demonstrate aerosol delivery of shRab25 as a therapeutic target for lung cancer treatment.

Rat strain differences in levels and effects of chronic inflammation due to intratracheal instillation of quartz on lung tumorigenesis induced by DHPN

Chronic inflammatory effects of single intratracheal instillation (i.t.) of quartz on rat lung tumorigenesis were examined using 4 different animal models. At first, in order to determine an appropriate dose of quartz i.t. to promote lung tumorigenesis, F344 male rats were administrated single 0, 0.5, 1, 2 or 4 mg quartz/rat after initiation by N-bis(2-hydroxypropyl) nitrosamine (DHPN). Further studies were performed to examine strain differences of the effects of chronic inflammation caused by quartz i.t. in 3 strains of rat, i.e. F344, Wistar-Hannover and SD. Each was instilled with 2mg quartz/rat after DHPN administration and sacrificed in week 24. In addition, strain differences in generation of inflammation were determined at days 1 and 28. Finally, for determination of long-term effects period, F344 and Wistar-Hannover rats were similarly treated, but the experiment was terminated at week 52. In F344 rats, the tumor areas in DHPN treated groups showed a tendency to increase along with the dose of quartz. F344 rats demonstrated the highest and Wistar-Hannover rats the lowest sensitivity to quartz in acute and chronic phases in the 3 strains. In 52 week, in F344 rats, the multiplicity of tumors and the serum concentration of IL-6 in the group treated with DHPN and quartz were significantly increased. The present experiments indicated that chronic inflammation due to quartz instillation exerted promoting effects on lung carcinogenesis in F344, SD and Wistar-Hannover rats. The strain differences in tumor promotion appeared to correlate with inflammatory reactions to quartz and increase of IL-6.

Napsin A is possibly useful marker to predict the tumorigenic potential of lung bronchiolo-alveolar hyperplasia in F344 rats

There are 2 types of bronchiolo-alveolar hyperplasia found in rat lungs. One is 'inflammatory hyperplasia' with a potential to recover in future with removal of the stimulating insult and the other is 'latent tumorigenic hyperplasia' as an independent preneoplastic lesion for adenocarcinoma. In the present experiment, we focused on rat lung bronchiolo-alveolar hyperplasia induced by 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK), which decreases with time after induction and reverts to normal, or by N-bis(2-hydroxypropyl)nitrosamine (DHPN), with tumorigenic potential to progress to adenoma and adenocarcinoma. Though NNK is a typical carcinogen inducing lung adenocarcinoma in female A/J mice, the tumorigenic potential by NNK in rats is weak. Differences between hyperplasias induced by DHPN and by NNK were here examined immunohistochemically. Formalin fixed paraffin embedded lung samples with hyperplastic and inflammatory lesions were obtained from rats exposed to DHPN or NNK and from lung inflammation models induced with fine particles like CuO, NiO and quartz. The 19 markers were examined immunohistochemically. Napsin A, in the inflammatory lesions and hyperplasia induced by NNK, was positive for macrophages and secretions in the alveoli spaces but less so in the walls of the alveoli. In the proliferative lesions including hyperplasia induced by DHPN, strong positive staining for napsin A was observed in the walls of the alveoli. Thus high expression was suggested to be possibly useful for detecting tumorigenic potential of rat lung hyperplasia.

Gender-dependent effects of gonadectomy on lung carcinogenesis by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in female and male A/J mice

The present study was conducted to investigate the effects of gonadectomy on lung carcinogenesis in female and male mice, and to determine an association between sex hormone and lung carcinogenesis. Female and male A/J mice were divided into gonadectomized and unoperated control groups and all animals were treated intraperitoneally with 1 or 2 injections of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) at the dose of 2 mg/mouse. The mice were sacrificed 18 or 56 weeks after surgery. Serum levels of estradiol in females and testosterone in males were confirmed to be decreased by gonadectomy. Lung white nodules were detected in all mice of all groups. In the control groups of 18- and 56-week studies, the multiplicities of lung nodules in females were significantly greater than in males. In males in the 56-week study, the multiplicity of macroscopical lung nodules, bronchiolo-alveolar hyperplasias, adenomas and tumors (adenomas and adenocarcinomas) showed significant increase with castration. In females in the 18-week study, the multiplicity of adenomas decreased significantly by ovariectomy. Based on the results of the present study, female A/J mice were confirmed to be more susceptible to NNK-induced lung carcinogenesis than males. Furthermore, it was suggested that the process is inhibited by testosterone and accelerated by estradiol. These findings indicate the possibility that sex hormones play important roles in determining sex differences in lung carcinogenesis in the A/J mice initiated by NNK.

A non-surgical method for induction of lung cancer in Wistar rats using a combination of NNK and high dietary fats

Lung cancer is one of the most common malignant neoplasms all over the world. Smoking and a number of constituents of tobacco are responsible for development of lung tumours; however, the deleterious effects of tobacco-derived carcinogen, nitrosamine 4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanone (nicotine-derived nitrosamine ketone (NNK)) remain unmatched. We report the development of a novel rodent model by administering multiple doses of NNK to male Wistar rats and feeding them with high-fat and low-protein diet. Tumour cells in lungs were observed in approximately 98 % rats after 8 months of NNK treatment, as evident by histopathological analysis. This rodent model showed slow progression of lung tumours which has helped us to assess early indicators of oxidative damage in lungs by studying the levels of lipid peroxidation and antioxidant parameters. LPO was elevated by 46.94 %, SOD, CAT, GSH and GR activity was decreased by 48.67 %, 22.04 %, 21.46 % and 20.85 %, respectively in serum of NNK treated rats when compared with control. These findings suggest that increased oxidative stress can represent a risk factor for the development of chronic disease in early future. This new animal model is an attempt to greatly facilitate studies of the pathophysiology, biochemistry and therapy of lung cancer.

Toxicity of nicotine by repeated intratracheal instillation to f344 rats

In vivo, nicotine in cigarette smoke induces various effects not only on the respiratory system but also the central and peripheral nerve systems, circulatory organs and digestive organs, and there is a possibility of promotion of lung tumorigenesis. The present experiment was conducted to examine histopathological changes caused by nicotine in the lung with repeated intratracheal instillation (i.t.). Six-week-old male F344 rats were administered nicotine by i.t. at doses of 0.05, 0.1 and 0.2 mg nicotine/rat every 3 weeks beginning at week 4, for up to a total of 9 times and were then sacrificed at week 30. The total number of administrations, total dose of nicotine and effective number of rats were 9 times, 0.45 mg and 5 rats and 4 times, 0.20 mg and 5 rats for the 0.05 mg nicotine/rat group; 3 times, 0.30 mg and 5 rats and 4 times, 0.40 mg and 3 rats for the 0.1 mg group; and 3 times, 0.60 mg and 3 rats for the 0.2 mg group, respectively. As a control group, 5 rats were administered 0.2 ml saline/rat 9 times. Some rats administered 0.1 and 0.2 mg nicotine suffered convulsions just after administration. Histopathologically, though proliferative changes were not observed, neutrophil infiltration, edema and fibrosis in the lung were induced by nicotine. In conclusion, repeated treatment of nicotine promoted neurologic symptoms in the acute phase, and strong inflammation in the lungs in the chronic phase, even at a low dose. Toxicity of nicotine is suggested to depend not on total dose of nicotine in the experiment but rather on repeated injury with consecutive administration.

NNK-Induced Lung Tumors: A Review of Animal Model

The incidence of lung adenocarcinoma has been remarkably increasing in recent years due to the introduction of filter cigarettes and secondary-hand smoking because the people are more exposed to higher amounts of nitrogen oxides, especially 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone(NNK), which is widely applied in animal model of lung tumors. In NNK-induced lung tumors, genetic mutation, chromosome instability, gene methylation, and activation of oncogenes have been found so as to disrupt the expression profiles of some proteins or enzymes in various cellular signal pathways. Transgenic animal with specific alteration of lung cancer-related molecules have also been introduced to clarify the molecular mechanisms of NNK in the pathogenesis and development of lung tumors. Based on these animal models, many antioxidant ingredients and antitumor chemotherapeutic agents have been proved to suppress the NNK-induced lung carcinogenesis. In the future, it is necessary to delineate the most potent biomarkers of NNK-induced lung tumorigenesis, and to develop efficient methods to fight against NNK-associated lung cancer using animal models.

Potassium octatitanate fibers (TISMO) induce pleural mesothelial cell reactions with iron accumulation in female A/J mice

It is crucial to develop therapeutic approaches for malignant mesothelioma, as well as to obtain information involving the possible mechanism involved in the development of mesothelioma. Subsequently, thoracotomy was performed to infuse test particles directly into the thoracic cavity of A/J mice. Fiber-shaped particles of potassium octatitanate (TISMO) and granular-shaped micro- and nano-size order particles of titanium dioxide (TiO(2)) were employed (1.5 mg in 0.2 ml saline/mouse). The experiment was terminated after 21 weeks to assess responses. Only the fiber-shaped TISMO, morphologically similar to asbestos, induced a severe reaction of the pleura. A number of TISMO fibers were observed in the alveoli, indicating penetration through the pleura. Following Berlin blue staining, positive spots were observed around the TISMO fibers, indicative of iron. These positive spots corresponded with cells that immunostained positively for calretinin, a marker of mesothelial cells. Similar observations were reported for asbestos-induced mesothelioma. The present study showed that only fiber-shaped TISMO induced severe reactions of the mesothelium in the pleura, and these involved iron accumulation derived from endogenous sources. The results indicate that the risk of mesothelial cell reaction does not depend on particle size, but may depend on shape.

Lack of promoting effects from physical pulmonary collapse in a female A/J mouse lung tumor initiated with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) with remarkable mesothelial cell reactions in the thoracic cavity by the polymer

Experimental identification of potential chemopreventive or tumor promotive agents in the lung is important. Establishment of short-term bioassay models is therefore a high priority. In an attempt to induce strong promotion effects, in Experiment 1, left thoracotomy was performed on A/J mice at week 3 after initiation with 4-(methylnitrosamno)-1-(3-pyridyl)-1-butanone (NNK) (2mg/0.1 ml saline/mouse i.p.) at weeks 0 and 1. In Experiment 2, at week 3, 0.2 ml of polymer gel was infused directly into the left cavity of the thorax with thoracotomy to occupy certain thoracic cavity volume and to examine the influence of physical pulmonary collapse. The experiments were terminated after 8, 10, 12 and 16 weeks in Experiment 1, and 12 weeks in Experiment 2 but no clear promotion effects in either experiment or pulmonary collapse due to infused polymer were apparent. However, a pronounced mesothelial cell reaction to the infused polymer was evident on the left lung surfaces and parietal pleura in Experiment 2. In conclusion, the present experiments did not demonstrate any clear lung tumor promotion effects of thoracotomy or physical left lung collapse. It remains possible, however, that alternative approaches might have greater efficacy and these need more consideration. In addition, mesothelial cells reaction was observed with the infused polymer.

Lack of Modifying Effects of Intratracheal Instillation of Quartz or Dextran Sulfate Sodium (DSS) in Drinking Water on Lung Tumor Development Initiated with 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in Female A/J Mice

The purpose of the present study was to investigate the effects of inflammation, induced by intratracheal instillation (i.t.) of quartz as an environmental factor in the lung or drinking of dextran sulfate sodium (DSS) as an environmental factor in the colon on lung tumors in female A/J mice initiated with NNK. For comparison, colonic preneoplastic lesions, aberrant crypt foci (ACF), were also assessed. A/J mice at 6 weeks of age were divided into 5 groups, and Groups 1, 2 and 3 were pretreated with NNK (2 mg / 0.1 ml saline / mouse, intraperitoneal injection) at week 0. For a week, 2% DSS in drinking water was administered to the mice in Groups 2 and 4 beginning in week 1. In week 2, the mice of Groups 3 and 5 were exposed to intratracheal instillation of quartz (0.1 mg/rat) suspended in 25 μl saline. The experiment was terminated after 16 weeks. The results for the lung tumors and colonic ACFs showed a lack of modifying effects of the inflammation in either site. Hematologically and histopathologically, the inflammation induced by 0.1 mg quartz in the lung and 2% DSS in the colon was lacking or only mild at the end of 16 weeks. These results suggest that there may be differences in sensitivity to inflammation that determine tumor promoting potential.

Update in neoplastic lung diseases and mesothelioma

CONTEXT

Lung cancer is a common disease frequently seen by the surgical pathologist. Although secondary to improvements in screening and radiologic techniques and aggressive resection of small pulmonary nodules, the diagnosis of preneoplastic lesions is increasing in frequency and importance. Consequently, a greater understanding of their role in the development of lung carcinoma is needed for optimal patient care. Two lesions often encountered as small pulmonary nodules are bronchioloalveolar carcinoma and adenocarcinoma, which can be challenging to distinguish. Recently, updates to the TNM classification of non-small cell lung carcinoma have been reported that directly impact prognosis and treatment algorithms. Identification of new molecular targets in pleural mesothelioma and in preneoplastic lesions may lead to improved therapeutic strategies.

OBJECTIVE

To present recent advances in our understanding of neoplastic lung diseases and mesothelioma and to describe how these advances relate to the current practice of pulmonary pathology.

DATA SOURCES

Published literature from PubMed (National Library of Medicine) and primary material from the authors' institution.

CONCLUSIONS

It is important for the surgical pathologist to understand current diagnostic classifications of non-small cell lung cancer and to be aware of the range of preneoplastic lesions, as well as the features useful for distinguishing bronchioloalveolar carcinoma from adenocarcinoma in small pulmonary nodules. Although pleural mesothelioma has distinct features, it can also overlap histologically with adenocarcinoma, and immunohistochemistry can greatly aid in accurate diagnosis. New therapies targeting molecular markers in both non-small cell lung cancer and mesothelioma rely on accurate histopathologic diagnosis of these entities.