Proteomic Changes in Oral Keratinocytes Chronically Exposed to Shisha (Water Pipe)

Cytotoxic and Genotoxic Effects of Waterpipe on Oral Health Status: Systematic review and meta-analysis

This systematic review and meta-analysis aimed to assess the cytotoxic and genotoxic impacts of waterpipe smoking on oral health. The databases MEDLINE, Cochrane Library and Dimensions were searched to find studies evaluating whether waterpipe smokers exhibited any cytotoxic or genotoxic effects on their oral cells compared to non-smokers, with regard to mouth neoplasms. Particularly, changes in DNA methylation and p53 expression were assessed. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were adopted for the systematic review. Review Manager was utilised for statistical analysis with a significance level at P <0.05. To assess the grades of the included articles, a risk of bias analysis was summarised. A forest plot, including some of the included articles included, was created regarding the different grades. A total of 20 studies were included in this review. The results showed that waterpipe smoking has cytotoxic and genotoxic effects on oral cells, with a risk difference of 0.16. Although the published articles are few in number, all confirm the devastating effects of waterpipe smoking related to the carcinogenicity. Waterpipe smoking is harmful to oral health. It causes a series of detrimental cellular and genetic modifications such as acanthosis, epithelial dysplasia and hyperparakeratosis. In addition, waterpipe smoke contains several carcinogenic compounds. As it releases many harmful organic compounds, waterpipe smoking increases the incidence of oral cancer.

Effects of smoking shisha, cancer risk, and strategies for prevention of shisha habit

Smoking tobacco through a water pipe, also referred to as Shisha, is prevalent in Middle Eastern countries but has gained popularity worldwide, especially among youth. The increasing global trend of shisha use is mainly led by misleading information about it being safe. The shisha smoke has potentially harmful chemicals, including several human carcinogens and other toxic products. There are recognised adverse effects on passive smokers exposed to second-hand smoke. It is a potential risk factor for several cancers and risks pregnant women and the foetus. A session of shisha smoking for 40 minutes is equivalent to smoking 100 or more cigarettes. There should be awareness about Shisha's harmful effects to reduce the risk to health through a coordinated global effort.

Signaling alterations in oral keratinocytes in response to shisha and crude tobacco extract

BACKGROUND

Tobacco consumption in smoking and non-smoking forms has been consequential in the rise of oral cancer cases. Among different forms, epidemiological studies from Middle Eastern countries and rural parts of northern India have reported increasing association of oral cancer with waterpipe (hookah) smoking. However, molecular mechanisms and role played by waterpipe smoking in the onset of oral carcinogenesis remains unexplored.

METHODS

In this study, immortalized normal human oral keratinocytes were chronically treated with extracts of two varieties of waterpipe tobacco-crude tobacco and processed shisha. Phenotypic changes and molecular aberrations were examined using cell culture-based assays and mass spectrometry-based quantitative proteomic analysis, respectively. Bioinformatics analysis was utilized to analyze proteomics data and identify dysregulated pathways.

RESULTS

Our data indicate that chronic treatment with waterpipe tobacco extracts increased proliferation, invasion, migration, and significant dysregulation of protein expression in oral keratinocytes. Altered expression of proteins involved in interferon signaling pathway were observed with both varieties of tobacco. Overexpression of cholesterol metabolism and vesicle-mediated transport proteins were identified exclusively in cells treated with crude tobacco extract. Bioinformatics analyses revealed different oncogenic response in oral cells based on the type of waterpipe tobacco used.

CONCLUSIONS

This study may serve as a useful resource in understanding the early onset of oral cancer attributed to waterpipe smoking.

Proteomic and phosphoproteomic profiling of shammah induced signaling in oral keratinocytes

Shammah is a smokeless tobacco product often mixed with lime, ash, black pepper and flavorings. Exposure to shammah has been linked with dental diseases and oral squamous cell carcinoma. There is limited literature on the prevalence of shammah and its role in pathobiology of oral cancer. In this study, we developed a cellular model to understand the effect of chronic shammah exposure on oral keratinocytes. Chronic exposure to shammah resulted in increased proliferation and invasiveness of non-transformed oral keratinocytes. Quantitative proteomics of shammah treated cells compared to untreated cells led to quantification of 4712 proteins of which 402 were found to be significantly altered. In addition, phosphoproteomics analysis of shammah treated cells compared to untreated revealed hyperphosphorylation of 36 proteins and hypophosphorylation of 83 proteins (twofold, p-value ≤ 0.05). Bioinformatics analysis of significantly altered proteins showed enrichment of proteins involved in extracellular matrix interactions, necroptosis and peroxisome mediated fatty acid oxidation. Kinase-Substrate Enrichment Analysis showed significant increase in activity of kinases such as ROCK1, RAF1, PRKCE and HIPK2 in shammah treated cells. These results provide better understanding of how shammah transforms non-neoplastic cells and warrants additional studies that may assist in improved early diagnosis and treatment of shammah induced oral cancer.

Waterpipe smoke condensate influences epithelial to mesenchymal transition and interferes with the cytotoxic immune response in non-small cell lung cancer cell lines

Waterpipe tobacco smoking (WPS) continues to spread globally and presents serious health hazards. The aim of the present study was to investigate the effects of treatment with WPS condensate (WPSC) on lung cell proliferation and plasticity as well as tumor cell recognition and killing by natural killer (NK) cells using cytotoxicity assays. The results indicated that exposure of normal and cancer lung cell lines to WPSC resulted in a decrease in their in vitro growth in a dose-dependent manner and it induced tumor senescence. In addition, WPSC selectively caused DNA damage as revealed by an increase in γH2AX and 53BP1 in tumor lung cells. To gain further insight into the molecular mechanisms altered by WPSC, we conducted a global comprehensive transcriptome analysis of WPSC-treated tumor cells. Data analysis identified an expression profile of genes that best distinguished treated and non-treated cells involving several pathways. Of these pathways, we focused on those involved in epithelial to mesenchymal transition (EMT) and stemness. Results showed that WPSC induced an increase in SNAI2 expression associated with EMT, ACTA2 and SERPINE2 were involved in invasion and CD44 was associated with stemness. Furthermore, WPSC exposure increased the expression of inflammatory response genes including CASP1, IL1B, IL6 and CCL2. While immune synapse formation between NK and WPSC-treated lung cancer target cells was not affected, the capacity of NK cells to kill these target cells was reduced. The data reported in the present study are, to the best of our knowledge, the first in vitro demonstration of WPSC effects on lung cellular parameters providing evidence of its potential involvement in tumor physiology and development.

In Vitro Methods to Simulate Pollution and Photo-Pollution Exposure in Human Skin Epidermis

Tissue homeostasis of an individual is a finely orchestrated phenomenon that ensures integrity and steady state in health. Emerging evidence indicates that the environment, especially ambient air pollution, has a lasting impact on this equilibrium (Beelen et al., Lancet 383:785-795, 2014). Environmental pollution consists of diverse entities, namely, particulate matter (PM 2.5, PM 10), ozone, and UV rays, among others (Heroux et al., Int J Public Health 60:619-627, 2015). Understandably, skin epidermis is the first and the most exposed tissue to such a wide range of substances and bears the assault. Previous studies have established that exposure to atmospheric pollution aggravates several skin disorders as, for instance, eczema, acne, lentigines or macules, and wrinkles (Araviiskaia et al., J Eur Acad Dermatol Venereol 33:1496-1505, 2019). While pollutants can interact with skin surface, contamination of deep skin by particulate matter (either ultrafine particles or by some polycyclic aromatic hydrocarbon (PAH) moieties) is also highly probable, particularly because PAH were detected in blood and inside the cortex of hair (Guo et al., Sci Total Environ 427-428:35-40, 2012; Palazzi et al., Environ Int 121:1341-1354, 2018). Importantly, concentrations of contaminant PAH in the blood are very low, in the nanomolar range (Neal et al., Reprod Toxicol 25:100-106, 2008); thus PAH levels in the skin might be in a similar range. Furthermore, it has been shown that some PAH (e.g., benzo[a]pyrene, indenopyrene) are phototoxic under UVA irradiation through a strong production of reactive oxygen species, ultimately leading to skin cancer in mice (Burke and Wei, Toxicol Ind Health 25:219-224, 2009). Since UVA1 (340-400 nm) can reach deep dermis, it can thus be assumed that photoactivation of PAH contaminants in living skin may locally induce a significant stress. In order to study the molecular mechanisms that are affected due to this exposure, there is an increasing need to develop reliable and diverse methods that simulate pollution exposure.

Chronic shisha exposure alters phosphoproteome of oral keratinocytes

Shisha smoking has been epidemiologically linked to oral cancer. However, few studies have investigated the pathobiology of shisha-induced cellular transformation. We studied the effects of chronic shisha exposure (8 months) in an in vitro model using immortalized, non-neoplastic oral keratinocytes (OKF6/TERT1). Quantitative proteomic and phosphoproteomic analyses were performed on OKF6/TERT1 cells treated with shisha extract for a period of 8 months. Pathway analysis was carried out to identify significantly enriched biological processes in shisha-treated cells. Chronic shisha exposure resulted in increased cell scattering phenomenon in OKF6/TERT1 cells. Data analysis revealed differential phosphorylation of 164 peptides (fold change ≥1.5, p ≤ 0.0.5) corresponding to 136 proteins. Proteins associated with mTORC1 and EIF4F complexes involved in initiating protein translation were seen to be enriched upon shisha treatment. Network analysis also highlighted downregulation of proteins involved in Type I interferon signaling in shisha-treated cells. Quantitative phosphoproteomic approach elucidated global perturbations to the molecular milieu of oral keratinocytes upon shisha exposure. Further studies are needed to validate putative targets in oral cancer patients with shisha smoking history.