Significance of the progesterone receptor and epidermal growth factor receptor, but not the estrogen receptor, in chemically induced lung carcinogenesis 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.

Expression of female sex hormone receptors and its relation to clinicopathological characteristics and prognosis of lung adenocarcinoma

BACKGROUND

Adenocarcinoma (ADC) of the lung exhibits different clinicopathological characteristics in men and women. Recent studies have suggested that these differences originate from the expression of female sex hormone receptors in tumor cells. The aim of the present study was to evaluate the immunohistochemical expression of female sex hormone receptors in lung ADC and determine the expression patterns in patients with different clinicopathological characteristics.

METHODS

A total of 84 patients with lung ADC who underwent surgical resection and/or core biopsy were recruited for the present study. Immunohistochemical staining was performed for estrogen receptor α (ERα), estrogen receptor β (ERβ), progesterone receptor (PR), epidermal growth factor receptor (EGFR), EGFR E746- A750 del, and EGFR L858R using tissue microarray.

RESULTS

A total of 39 (46.4%) ERα-positive, 71 (84.5%) ERβ-positive, and 46 (54.8%) PR-positive lung ADCs were identified. In addition, there were 81 (96.4%) EGFR-positive, 14 (16.7%) EGFR E746-A750 del-positive, and 34 (40.5%) EGFR L858R-positive cases. The expression of female sex hormone receptors was not significantly different in clinicopathologically different subsets of lung ADC.

CONCLUSIONS

Expression of female sex hormone receptors is not associated with the prognosis and clinicopathological characteristics of patients with lung ADC.

Testing Novel Pyrimidinyl Rexinoids: A New Paradigm for Evaluating Rexinoids for Cancer Prevention

Rexinoids, selective ligands for retinoid X receptors (RXR), have shown promise in preventing many types of cancer. However, the limited efficacy and undesirable lipidemic side-effects of the only clinically approved rexinoid, bexarotene, drive the search for new and better rexinoids. Here we report the evaluation of novel pyrimidinyl (Py) analogues of two known chemopreventive rexinoids, bexarotene (Bex) and LG100268 (LG268) in a new paradigm. We show that these novel derivatives were more effective agents than bexarotene for preventing lung carcinogenesis induced by a carcinogen. In addition, these new analogues have an improved safety profile. PyBex caused less elevation of plasma triglyceride levels than bexarotene, while PyLG268 reduced plasma cholesterol levels and hepatomegaly compared with LG100268. Notably, this new paradigm mechanistically emphasizes the immunomodulatory and anti-inflammatory activities of rexinoids. We reveal new immunomodulatory actions of the above rexinoids, especially their ability to diminish the percentage of macrophages and myeloid-derived suppressor cells in the lung and to redirect activation of M2 macrophages. The rexinoids also potently inhibit critical inflammatory mediators including IL6, IL1β, CCL9, and nitric oxide synthase (iNOS) induced by lipopolysaccharide. Moreover, in vitro iNOS and SREBP (sterol regulatory element-binding protein) induction assays correlate with in vivo efficacy and toxicity, respectively. Our results not only report novel pyrimidine derivatives of existing rexinoids, but also describe a series of biological screening assays that will guide the synthesis of additional rexinoids. Further progress in rexinoid synthesis, potency, and safety should eventually lead to a clinically acceptable and useful new drug for patients with cancer.

Production of amphiregulin and recovery from influenza is greater in males than females

Background

Amphiregulin (AREG) is an epidermal growth factor that is a significant mediator of tissue repair at mucosal sites, including in the lungs during influenza A virus (IAV) infection. Previous research illustrates that males of reproductive ages experience less severe disease and recover faster than females following infection with IAV.

Methods

Whether males and females differentially produce and utilize AREG for pulmonary repair after IAV infection was investigated using murine models on a C57BL/6 background and primary mouse and human epithelial cell culture systems.

Results

Following sublethal infection with 2009 H1N1 IAV, adult female mice experienced greater morbidity and pulmonary inflammation during the acute phase of infection as well as worse pulmonary function during the recovery phase of infection than males, despite having similar virus clearance kinetics. As compared with females, AREG expression was greater in the lungs of male mice as well as in primary respiratory epithelial cells derived from mouse and human male donors, in response to H1N1 IAVs. Internalization of the epidermal growth factor receptor (EGFR) was also greater in respiratory epithelial cells derived from male than female mice. IAV infection of Areg knock-out (Areg^−/−) mice eliminated sex differences in IAV pathogenesis, with a more significant role for AREG in infection of male compared to female mice. Deletion of Areg had no effect on virus replication kinetics in either sex. Gonadectomy and treatment of either wild-type or Areg^−/− males with testosterone improved the outcome of IAV as compared with their placebo-treated conspecifics.

Conclusions

Taken together, these data show that elevated levels of testosterone and AREG, either independently or in combination, improve resilience (i.e., repair and recovery of damaged tissue) and contribute to better influenza outcomes in males compared with females.

Prognostic significance of aromatase and estrogen receptor beta expression in EGFR wild-type lung adenocarcinoma

OBJECTIVES

Based on recent findings of aromatase and estrogen receptor beta (ERβ) expression in non-small-cell lung cancer, we assessed the clinicopathological and prognostic significance of aromatase and ERβ expression and their relationship to epidermal growth factor receptor (EGFR) mutation in lung adenocarcinoma.

MATERIALS AND METHODS

We evaluated 150 resected primary lung adenocarcinoma specimens. Expression of aromatase, ERα, ERβ, progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) was evaluated by immunostaining, and EGFR and KRAS mutations were analyzed. Overall survival (OS) and recurrence-free survival (RFS) were calculated using the Kaplan-Meier method.

RESULTS

Expression of aromatase, ERα, ERβ, PR, and HER2 was detected in 88.0%, 1.3%, 79.3%, 2.7%, and 39.3% of specimens, respectively. In patients with EGFR wild-type lung adenocarcinoma, high aromatase expression was an independent predictor of poor OS (hazard ratio [HR]=2.638; 95% confidence interval [CI], 1.173-5.936; P=.019) and RFS (HR=2.505; 95% CI, 1.154-5.434; P=.020). Positive ERβ expression was also an independent predictor of poor RFS (HR=4.013; 95% CI, 1.219-13.207; P=.022). Furthermore, high aromatase expression was a significant predictor of poor survival only in females (OS, P=.010; RFS, P=.007), whereas positive ERβ expression was an important predictor of poor survival only in males (OS, P=.073; RFS, P=.051). No prognostic significance was observed in patients with EGFR mutations.

CONCLUSIONS

Our findings suggest that EGFR wild-type lung adenocarcinoma is an estrogen-dependent carcinoma, and aromatase expression and ERβ expression are potent prognostic markers for EGFR wild-type lung adenocarcinoma.

Complete mitochondrial genome sequence and mutations of the lung carcinoma model inbred C57BL/6 mice strain

In the present work, we undertook the complete mitochondrial genome sequencing of an important lung carcinoma model inbred rat strain for the first time. The total length of the mitogenome was 16,308 bp. It harbored 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, and one non-coding control region (D-loop region). The mutation events were also reported.