AKR1C1 as a Biomarker for Differentiating the Biological Effects of Combustible from Non-Combustible Tobacco Products

Nicotine mediated epithelial modulations: An in-vitro evidence

Introduction

Nicotine, the main ingredient in tobacco, acts as a key alkaloid of nearly all tobacco products and has been demonstrated to facilitate tumorigenesis and accelerate metastasis. Further traditional tobacco products have shown to give systemic oral effects such as vasoconstriction, inflammation, and delayed wound healing, however; none of the reports have confirmed the significant knowledge of oral sequel of the effect of nicotine on oral epithelial cells. So, the current study aimed to investigate the effect of nicotine on epithelial transformation to a malignant state.

Material & methods

Through in-vitro experiments, the effects of nicotine on epithelial cells obtained from nicotine never exposed buccal mucosa were analyzed using total count and viability test, proliferation assay, cell cycle distribution assay, and PI3K/MAPK dual pathway activation assay.

Result & conclusion

MTT assay demonstrated that the proliferation of epithelial cells takes place at a 150 mM concentration of nicotine. Further, we identified the significantly increased cell count and viability in nicotine-exposed cells. Further, cell cycle distribution assay results demonstrated that nicotine forced the epithelial cells to enter the first growth phase. The same influence of nicotine was observed on the PI3K/MAPK dual pathway activation assay where a greater number of nicotine exposed cells showed dual pathway activation. In conclusion, the current study determined the potential mechanism of action of nicotine on oral epithelial cell proliferation through activating the oncogenic pathway. This may help to develop novel therapeutic strategies for the prevention of malignant transformation from smokeless tobacco-caused oral cancer.

SERPINE1 as an Independent Prognostic Marker and Therapeutic Target for Nicotine-Related Oral Carcinoma

OBJECTIVES

Nicotine is an ingredient of tobacco, and exposure to nicotine increases the risks of various cancers, including oral cancer. Previous studies have focused on the addictive properties of nicotine, but its carcinogenic mechanism has rarely been studied. We aimed to explore the key genes in the process through which nicotine promotes the occurrence and development of oral cancer via data mining and experimental verification.

METHODS

This study involved three parts. First, key genes related to nicotine-related oral cancer were screened through data mining; second, the expression and clinical significance of a key gene in oral cancer tissues were verified by bioinformatics. Finally, the expression and clinical significance of the key gene in oral cancer were histologically investigated, and the effects of its expression on cell proliferation, invasion, and drug resistance were cytologically assessed.

RESULTS

SERPINE1 was identified as the key gene, which was upregulated in nicotine-treated oral cells and may be an independent prognostic factor for oral cancer. SERPINE1 was enriched in various pathways, such as the tumor necrosis factor and apelin pathways, and was related to the infiltration of macrophages, CD4+T cells, and CD8+T cells. Overexpression of SERPINE1 was associated with N staging and may be involved in hypoxia, angiogenesis, and metastasis. Knockdown of SERPINE1 in oral cancer cells resulted in weakened cell proliferation and invasion ability and increased sensitivity to bleomycin and docetaxel.

CONCLUSION

This study revealed SERPINE1 as a key gene for nicotine-related oral cancer, indicating that SERPINE1 may be a novel prognostic indicator and therapeutic target for oral carcinoma.

TMED2/9/10 Serve as Biomarkers for Poor Prognosis in Head and Neck Squamous Carcinoma

Background: Head and neck squamous carcinoma (HNSC) is one of the most common malignant tumors with high incidence and poor prognosis. Transmembrane emp24 structural domain (TMED) proteins are involved in protein transport and vesicle budding processes, which have implicated various malignancies’ progression. However, the roles of TMEDs in HNSC, especially in terms of development and prognosis, have not been fully elucidated.

Methods: We applied TIMER 2.0, UALCAN, GEPIA 2, Kaplan-Meier plotter, GEO, The Human Protein Atlas (HPA), cBioPortal, Linkedomics, Metascape, GRNdb, STRING, and Cytoscape to investigate the roles of TMED family members in HNSC.

Results: Compared with normal tissues, the mRNA expression levels of TMED1/2/4/5/7/8/9/10 were significantly increased in the TCGA HNSC dataset. And we combined GEPIA 2 and Kaplan-Meier Plotter to select TMED2/9/10 with prognostic value. Then we detected the levels of mRNA in the GEO HNSC database and the protein expression in HPA. It was found that the mRNA and protein expression levels of TMED2/9/10 were increased in HNSC. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that TMED2/9/10 and their co-expressed genes promoted the malignant behavior of tumors by participating in biological processes such as intracellular transferase complex, protein transport, focal adhesion, intracellular protein processing. Single-cell analysis and immune infiltration analysis suggested that immune responses of cancer-associated fibroblasts and endothelial cells might be associated with prognosis. Finally, the transcription factors-genes network and protein-protein functional interaction network pointed to genes such as X-box binding protein 1 (XBP1) and TMED7, which might cooperate with TMED2/9/10 to change the progression of HNSC.

Conclusions: Our study implied that TMED2/9/10 and related genes mightjointly affect the prognosis of HNSC, providing specific clues for further experimental research, personalized diagnosis strategies, and targeted clinical therapy for HNSC.

Genome-wide evaluation of transcriptomic responses of human tissues to smoke: A systems biology study

The harmful compounds in various sources of smoke threaten human health. So far, many studies have investigated the effects of compounds of smoke on transcriptome changes in different human tissues. However, no study has been conducted on the effects of these compounds on transcriptome changes in different human tissues simultaneously. Hence, the present study was conducted to identify smoke-related genes (SRGs) and their response mechanisms to smoke in various human cells and tissues using systems biology based methods. A total of 6,484 SRGs were identified in the studied tissues, among which 4,095 SRGs were up-regulated and 2,389 SRGs were down-regulated. Totally, 459 SRGs were smoke-related transcription factors (SRTFs). Gene regulatory network analysis showed that the studied cells and tissues have different gene regulation and responses to compounds of smoke. The comparison of different tissues revealed no common SRG among the all studied tissues. However, the CYP1B1 gene was common among seven cells and tissues, and had the same expression trend. Network analysis showed that the CYP1B1 is a hub gene among SRGs in various cells and tissues. To the best of our knowledge, for the first time, our results showed that compounds of smoke induce and increase the expression of CYP1B1 key gene in all target and non-target tissues of human. Moreover, despite the specific characteristics of CYP1B1 gene and its identical expression trend in target and non-target tissues, it can be used as a biomarker for diagnosis and prognosis.

Aqueous extract of tobacco induces mitochondrial potential dependent cell death and epithelial-mesenchymal transition in gingival epithelial cells

Smokeless tobacco habits are detrimental to oral health. A correlation between tobacco use and local epithelial tissue damage exists. Yet, the underlying cellular mechanism is not precisely characterized. This study assessed the dose-dependent action of Smokeless tobacco extract on gingival epithelial cells. Gingival tissue was taken from 5 healthy donors. Gingival epithelial cells were isolated by an enzymatic method and cultured up to passage 2. The cultured cells were treated with smokeless tobacco extract at 10%, 25%, 50%, and 75% volume concentration. After 48 h of incubation, MTT assay, Annexin V/PI assay, and DiIC1(5) assay were used to evaluate viability, apoptosis, and mitochondrial potential of the cells. RT-qPCR was used to determine the expression of BAX, BCL2, ECAD, NCAD, and TWIST. The Smokeless tobacco extract reduced cell viability by disrupting the mitochondrial potential and inducing apoptosis. Further, the Smokeless tobacco extract induced a dose-dependent epithelial-mesenchymal-transition in gingival epithelial cells. Apoptotic cellular death caused by tobacco extract on the gingival epithelial system was dependant on the mitochondrial potential of the cell. The results demonstrate that smokeless tobacco causes detrimental metabolic alterations of the periodontium.

Featured application

This study elucidates the mechanism by which Smokeless tobacco products cause cellular damage to the gingival epithelium. The use of Smokeless tobacco products can lead to major cellular and surface changes in the gingiva and its appearance. The consequences of these changes are not limited to oral cancer but also increases a person's risk for dental and periodontal disease.

AKR1C1 Contributes to Cervical Cancer Progression via Regulating TWIST1 Expression

Cervical cancer (CC) is a common gynecological malignancy, accounting for 10% of all gynecological cancers. Recently, targeted therapy for CC has shown unprecedented advantages. To improve CC patients' prognosis, there are still urgent needs to develop more promising therapeutic targets. Aldo-keto reductase 1 family member C1 (AKR1C1) is a type of aldosterone reductase and plays a regulatory role in a variety of key metabolic pathways. Several studies indicated that AKR1C1 was highly expressed in a series of tumors, and participated in the progression of these tumors. However, the possible effects of AKR1C1 on CC progression remain unclear. Herein, we revealed AKR1C1 was highly expressed in human CC tissues and correlated with the clinical characteristics of patients with CC. AKR1C1 could regulate the proliferation and invasion of cervical cancer cells in vitro. Further experiments showed that AKR1C1 could regulate TWIST1 expression and AKT pathway. In summary, we confirmed the involvement of AKR1C1 in CC progression, and therefore AKR1C1 may have the potential to be a molecular target for CC treatment.

Distinct gene expression changes in human peripheral blood mononuclear cells treated with different tobacco product preparations

Cigarette smoking exerts diverse physiological effects including immune suppression. To better characterize the biological effects of different categories of tobacco products, a genome-wide gene expression study was performed. Transcriptomic profiling was performed in PBMCs treated with different equi-nicotine units of aqueous extracts of cigarette smoke (termed Whole Smoke-Conditioned Medium, or WS-CM), or a single dose smokeless tobacco extract (STE) prepared from reference tobacco products. WS-CM induced dose-dependent changes in the expression of several genes. No significant expression differences between low WS-CM and media control were detected. However, transcripts were significantly affected by medium WS-CM (479), high WS-CM (2, 703), and STE (2, 156). The overlap between medium WS-CM and STE, and high WS-CM and STE, was minimal (34 and 65 transcripts, respectively). Hierarchical clustering revealed that gene expression profiles for STE and medium WS-CM co-clustered, while those affected by the high dose of WS-CM clustered distinctly. Functional analysis revealed that WS-CM, but not STE, uniquely affected genes involved in immune cell development and inflammatory response. Cascades of upstream regulators (e.g., TNF, IL1β, NFƙB) were identified for the observed gene expression changes and generally suppressed by WS-CM, but not by STE. Collectively, these findings demonstrate that combustible and non-combustible tobacco products elicit distinct biological effects, which could explain the observed chronic immune suppression in smokers.

Nicotine induces oral dysplastic keratinocyte migration via fatty acid synthase-dependent epidermal growth factor receptor activation

Despite advances in diagnostic and therapeutic management, oral squamous cell carcinoma (OSCC) patient survival rates have remained relatively unchanged. Thus, identifying early triggers of malignant progression is critical to prevent OSCC development. Traditionally, OSCC initiation is elicited by the frequent and direct exposure to multiple tobacco-derived carcinogens, and not by the nicotine contained in tobacco products. However, other nicotine-containing products, especially the increasingly popular electronic cigarettes (e-cigs), have unknown effects on the progression of undiagnosed tobacco-induced oral premalignant lesions, specifically in regard to the effects of nicotine. Overexpression of fatty acid synthase (FASN), a key hepatic de novo lipogenic enzyme, is linked to poor OSCC patient survival. Nicotine upregulates hepatic FASN, but whether this response occurs in oral dysplastic keratinocytes is unknown. We hypothesized that in oral dysplastic keratinocytes, nicotine triggers a migratory phenotype through FASN-dependent epidermal growth factor receptor (EGFR) activation, a common pro-oncogenic event supporting oral carcinogenesis. We report that in oral dysplastic cells, nicotine markedly upregulates FASN leading to FASN-dependent EGFR activation and increased cell migration. These results raise potential concerns about e-cig safety, especially when used by former tobacco smokers with occult oral premalignant lesions where nicotine could trigger oncogenic signals commonly associated with malignant progression.

Molecular alterations associated with chronic exposure to cigarette smoke and chewing tobacco in normal oral keratinocytes

Tobacco usage is a known risk factor associated with development of oral cancer. It is mainly consumed in two different forms (smoking and chewing) that vary in their composition and methods of intake. Despite being the leading cause of oral cancer, molecular alterations induced by tobacco are poorly understood. We therefore sought to investigate the adverse effects of cigarette smoke/chewing tobacco exposure in oral keratinocytes (OKF6/TERT1). OKF6/TERT1 cells acquired oncogenic phenotype after treating with cigarette smoke/chewing tobacco for a period of 8 months. We employed whole exome sequencing (WES) and quantitative proteomics to investigate the molecular alterations in oral keratinocytes chronically exposed to smoke/ chewing tobacco. Exome sequencing revealed distinct mutational spectrum and copy number alterations in smoke/ chewing tobacco treated cells. We also observed differences in proteomic alterations. Proteins downstream of MAPK1 and EGFR were dysregulated in smoke and chewing tobacco exposed cells, respectively. This study can serve as a reference for fundamental damages on oral cells as a consequence of exposure to different forms of tobacco.

Polymorphisms in XRCC1, ERCC2, and ERCC3 DNA repair genes, CYP1A1 xenobiotic metabolism gene, and tobacco are associated with bladder cancer susceptibility in Tunisian population

Other than the established environmental risk factors associated with bladder cancer (BC), little is known about the genetic variations determining the individual susceptibility of this complex disease. This study aimed to investigate the relationship of BC with environmental agents and polymorphisms in XRCC1, ERCC2, and ERCC3 DNA repair genes and CYP1A1, CYP2D6, NAT1, and NAT2 xenobiotic metabolism genes through a hospital-based case-control study in Tunisia. The selection of the single nucleotide polymorphisms (SNPs) (rs25487, rs 13181, rs415407, rs446421, rs1058172, rs4921880, and rs1208) was performed using the dbSNP database. DNA genotyping was determined by PCR-RFLP after DNA extraction from whole blood. The risks of BC associated with every polymorphism as well as the studied environmental factors were estimated by multivariate-adjusted logistic regression using R software. In addition, gene-gene interactions were analyzed using generalized multifactor dimensionality reduction (GMDR) methods. Results showed that tobacco smoking and chewing parameters were significantly associated with BC risk. Single-gene variant analysis showed significant associations of the TT genotype of CYP1A1 and the rare GG genotype of ERCC2 with bladder cancer susceptibility (OR = 1.34, 95% CI 1.22-1.40, P < 0.0001). According to GMDR analysis, our findings indicated a significant association between BC and gene-gene interaction among the CYP1A1, ERCC3, and XRCC1. The present results suggest a potential role of XRCC1, ERCC2, ERCC3, and CYP1A1 besides tobacco intake in susceptibility to BC.

Greater Sensitivity of Oral Fibroblasts to Smoked Versus Smokeless Tobacco

BACKGROUND

Smokers have an increased incidence and severity of periodontal disease. Although cigarette smoke contains >4,000 chemical components that could affect periodontal tissues, less is understood about the effect of smokeless tobacco. Therefore, this study compares the effects of cigarette smoke extract (CSE) and smokeless tobacco extract (STE) on cell survival and motility of periodontal ligament (PDL) and gingival fibroblasts in vitro.

METHODS

PDL and gingival fibroblasts were exposed to various concentrations of CSE, STE, or nicotine alone. Viable cells were labeled with calcein acetoxymethyl, visualized using fluorescent microscopy, and quantified using a fluorescence multi-well plate reader. In vitro wounding and collagen gel contraction assays were used to assess cell motility.

RESULTS

Both gingival and PDL fibroblasts displayed reduced cell viability with increasing concentrations of CSE and STE. Based on relative nicotine content, CSE was significantly more cytotoxic than STE. PDL fibroblasts were also more sensitive to both CSE and STE compared with gingival fibroblasts. Finally, sublethal doses of CSE reduced cell motility and gel contraction, whereas STE had less effect. Nicotine alone ≤0.5 mM had little to no effect in any of these assays.

CONCLUSIONS

Many of the underlying effects of tobacco products on periodontal tissues may be due to direct inhibition of normal fibroblast function. CSE is found to be more deleterious to the function of both PDL and gingival fibroblasts than STE. PDL fibroblasts appear to be more sensitive to CSE and STE than gingival fibroblasts. Therefore, cigarette smoke may have more profound effects than smokeless tobacco.