Down-regulation of circulating microRNA let-7a in Egyptian smokers

FGFR3 and FGFR4 overexpression in juvenile nasopharyngeal angiofibroma: impact of smoking history and implications for personalized management

Lifestyle factors, including smoking, have been linked to neoplastic diseases, and reports suggest an association between smoking and overexpression of FGFR (fibroblast growth factor receptor) in certain neoplasms. This study aims to assess the expression of FGFR3 and FGFR4 genes in patients with and without a history of smoking.A total of 118 participants were recruited, including 83 Juvenile Nasopharyngeal Angiofibroma (JNA) patients and 35 healthy participants, the JNA patients were further stratified as smokers and nonsmokers. Total RNA was extracted from the blood & saliva sample by using TRIzol reagent, and quantified using a Nanodrop, and then subjected to gene expression analysis of FGFR3/4 using RT-PCR. Immunohistochemistry analysis was employed using fresh biopsies of JNA to validate the findings. All experiments were performed in triplicates and analysed using the Chi-Square test (P < 0.05). Smokers exhibited significantly lower total RNA concentrations across all sample types (P < 0.001). The study revealed significant upregulation of both FGFR3/4 genes in JNA patients (P < 0.05). Moreover, FGFR3 expression was significantly higher among smokers 66% (95% CI: 53-79%) compared to non-smokers 22% (95% CI: 18-26%). Immunohistochemistry analysis demonstrated moderate to strong staining intensity for FGFR3 among smokers. The study highlights the overexpression of FGFR3/4 genes in JNA patients, with a stronger association observed among smokers. Furthermore, medical reports indicated higher rates of recurrence and bleeding intensity among smokers. These findings emphasize the potential role of FGFR3 as a key molecular factor in JNA, particularly in the context of smoking.

Let-7a Downregulation Accompanied by KRAS Mutation Is Predictive of Lung Cancer Onset in Cigarette Smoke-Exposed Mice

BACKGROUND

Let-7 is a tumor suppressor microRNA targeting the KRAS lung oncogene. Let-7a downregulation is reversible during the early stages of lung carcinogenesis but is irreversible in cancer cells. The aim of this study is to shed light on the relationship between oncogene (KRAS) mutation and let-7a downregulation in cigarette smoke (CS)-induced lung carcinogenesis.

METHODS

A total of 184 strain H Swiss albino mice were either unexposed (control) or exposed to CS for 2 weeks (short CS) or 8 months (long CS). After 8 months, the lungs were individually collected. The following end points have been evaluated: (a) DNA methylation of the let-7a gene promoter by bisulphite-PCR and pyrosequencing; (b) let-7a expression by qPCR; (c) KRAS mutation by DNA pyrosequencing; (d) cancer incidence by histopathological examination.

RESULTS

let-7a expression decreased by 8.3% in the mice exposed to CS for two weeks (CS short) and by 33.4% (p ≤ 0.01) in the mice exposed to CS for 8 months (CS long). No significant difference was detected in the rate of let-7a-promoter methylation between the Sham-exposed mice (55.1%) and the CS short-(53%) or CS long (51%)-exposed mice. The percentage of G/T transversions in KRAS codons 12 and 13 increased from 2.3% (Sham) to 6.4% in CS short- and to 11.5% in CS long-exposed mice. Cancer incidence increased significantly in the CS long-exposed mice (11%) as compared to both the Sham (4%) and the CS short-exposed (2%) mice. In the CS long-exposed mice, the correlation between let-7a expression and the number of KRAS mutations was positive (R = +0.5506) in the cancer-free mice and negative (R = -0.5568) in the cancer-bearing mice.

CONCLUSIONS

The effects of CS-induced mutations in KRAS are neutralized by the high expression of let-7a in cancer-free mice (positive correlation) but not in cancer-bearing mice where an irreversible let-7a downregulation occurs (negative correlation). This result provides evidence that both genetic (high load of KRAS mutation) and epigenetic alterations (let-7a irreversible downregulation) are required to produce lung cancer in CS-exposed organisms.

The influence of lifestyle factors on miRNA expression and signal pathways: a review

The term 'lifestyle' includes different factors that contribute to the maintenance of a good health status. Increasing evidences suggest that lifestyle factors may influence epigenetic mechanisms, such as miRNAs expression. The dysregulation of miRNAs can modify the expression of genes and molecular pathways that may lead to functional alterations. This review summarizes human studies highlighting that diet, physical activity, smoking and alcohol consumption may affect the miRNA machinery and several biological functions. Most miRNAs are involved in molecular pathways that influence inflammation, cell cycle regulation and carcinogenesis resulting in the onset or progression of pathological conditions. Investigating these interactions will be pivotal for understanding the etiology of pathologic processes, the potential new treatment strategies and for preventing diseases.

Smoking load reduction is insufficient to downregulate miR-301b, a lung cancer promoter

Several circulating miRNAs identified in the plasma of smokers have been implicated as promoters of nasopharyngeal and lung carcinoma. To investigate the plasma profile of miRNAs in subjects who reduces the number of smoked cigarettes and who quit after six months. We accompanied 28 individuals enrolled in a Smoking Cessation Program over 6 months. At Baseline, clinical characteristics, co-morbidities, and smoking history were similar among subjects. After 6 months, two groups were defined: who successfully quitted smoking (named "quitters", n = 18, mean age 57 years, 11 male) and who reduced the number of cigarettes smoked (20-90%) but failed to quit smoking (named "smokers", n = 10, mean age 52 years, 3 male). No significant clinical changes were observed between groups at baseline and after a 6-month period, however, quitters showed significant downregulations in seven miRNAs at baseline: miR-17 (- 2.90-fold, p = 0.029), miR-20a (- 3.80-fold, p = 0.021); miR-20b (- 4.71-fold, p = 0.027); miR-30a (- 3.95-fold, p = 0.024); miR-93 (- 3.63-fold, p = 0.022); miR-125a (- 1.70-fold, p = 0.038); and miR-195 (- 5.37-fold, p = 0.002), and after a 6-month period in 6 miRNAs: miR-17 (- 5.30-fold, p = 0.012), miR-20a (- 2.04-fold, p = 0.017), miR-20b (- 5.44-fold, p = 0.017), miR-93 (- 4.00-fold, p = 0.041), miR-101 (- 4.82-fold, p = 0.047) and miR-125b (- 3.65-fold, p = 0.025). Using time comparisons, only quitters had significant downregulation in miR-301b (- 2.29-fold, p = 0.038) after 6-month. Reductions in the number of smoked cigarettes was insufficient to change the plasma profile of miRNA after 6 months. Only quitting smoking (100% reduction) significantly downregulated miR-301b related to hypoxic conditions, promotion of cell proliferation, decreases in apoptosis, cancer development, and progression as increases in radiotherapy and chemotherapy resistance.

Machine Learning Approach for Predicting Past Environmental Exposures From Molecular Profiling of Post-Exposure Human Serum Samples

OBJECTIVE

To develop an approach for a retrospective analysis of post-exposure serum samples using diverse molecular profiles.

METHODS

The 236 molecular profiles from 800 de-identified human serum samples from the Department of Defense Serum Repository were classified as smokers or non-smokers based on direct measurement of serum cotinine levels. A machine-learning pipeline was used to classify smokers and non-smokers from their molecular profiles.

RESULTS

The refined supervised support vector machines with recursive feature elimination predicted smokers and non-smokers with 78% accuracy on the independent held-out set. Several of the identified classifiers of smoking status have previously been reported and four additional miRNAs were validated with experimental tobacco smoke exposure in mice, supporting the computational approach.

CONCLUSIONS

We developed and validated a pipeline that shows retrospective analysis of post-exposure serum samples can identify environmental exposures.

Association between circulating microRNA-126 expression level and tumour necrosis factor alpha in healthy smokers

Introduction: Smoking contributes to the death of a million people worldwide each year. Smokers experience an alteration in tumour necrosis factor-alpha (TNF-α), and the risk of expected lung cancer. The study aimed at investigating the expression levels of mir-126 and mir-124, as well as TNF-α as possible biomarkers of expected smoking-related diseases. Methods: Twenty-five male smokers' age and sex-matched with 25 non-smokers were recruited for the present study. Plasma expression levels of mir-126 and mir-124 were evaluated using quantitative real-time PCR. Lipid profile, TNF-α, interleukin-6 and C-reactive protein were assessed in plasma of each participant. Results: Plasma miR-126 was statistically down-regulated in smokers relative to non-smokers; however, mir-124 did not show any significant changes between groups. Among the measured parameters, mir-126 and tumour necrosis factor alpha (TNF-α) displayed a good discrimination and sensitivity between smokers and non-smokers (AUC = 0.809 (95% CI: 0.668-0.95; p < 0.001) and 0.742(95% CI: 0.584-0.9; p < 0.01), respectively. Also, the combined evaluation of miR-126 and TNF-α levels showed high discrimination (AUC= 0.889 (95% CI: 0.779-1.00; p < 0.0001), sensitivity = 85%, and specificity = 80% in the diagnosis of smokers with non-smokers. Conclusions: MiR-126 and TNF-α are potential biomarkers of smoking-related diseases and are important in assessing the expected tobacco-related harm.