Immunohistochemical Analysis of the Activation Status of the Akt/mTOR/pS6 Signaling Pathway in Oral Lichen Planus

Urolithin A, induces apoptosis and autophagy crosstalk in Oral Squamous Cell Carcinoma via mTOR /AKT/ERK1/2 pathway

BACKGROUND

Oral squamous cell carcinoma (OSCC) is the most prevalent malignancy in the world with an alarming rate of mortality. Despite the advancement in treatment strategies and drug developments, the overall survival rate remains poor. Therefore, it is imperative to develop alternative or complimentary anti cancer drugs with minimum off target effects. Urolithin A, a microbial metabolite of ellagic acid and ellagitannins produced endogenously by human gut micro biome is considered to have anti-cancerous activity. However anti tumorigenic effect of urolithin A in OSCC is yet to be elucidated. In this study, we examined whether urolithin A inhibits cell growth and induces both apoptosis and autophagy dependent cell death in OSCC cell lines.

PURPOSE

The present study aims to evaluate the potential of urolithin A to inhibit OSCC and its regulatory effect on OSCC proliferation and invasion in vitro and in vivo mouse models.

METHODS

We evaluated whether urolithin A could induce cell death in OSCC in vitro and in vivo mouse models.

RESULTS

Flow cytometric and immunoblot analysis on Urolithin A treated OSCC cell lines revealed that urolithin A markedly induced cell death of OSCC via the induction of endoplasmic reticulum stress and subsequent inhibition of AKT and mTOR signaling as evidenced by decreased levels of phosphorylated mTOR and 4EBP1. This further revealed a possible cross talk between apoptotic and autophagic signaling pathways. In vivo study demonstrated that urolithin A treatment reduced tumor size and showed a decrease in mTOR, ERK1/2 and Akt levels along with a decrease in proliferation marker, Ki67. Taken together, in vitro as well as our in vivo data indicates that urolithin A is a potential anticancer agent and the inhibition of AKT/mTOR/ERK signalling is crucial in Urolithin A induced growth suppression in oral cancer.

CONCLUSION

Urolithin A exerts its anti tumorigenic activity through the induction of apoptotic and autophagy pathways in OSCC. Our findings suggest that urolithin A markedly induced cell death of oral squamous cell carcinoma via the induction of endoplasmic reticulum stress and subsequent inhibition of AKT and mTOR signaling as evidenced by decreased levels of phosphorylated mTOR and 4EBP1. Urolithin A remarkably suppressed tumor growth in both in vitro and in vivo mouse models signifying its potential as an anticancer agent in the prevention and treatment of OSCC. Henceforth, our findings provide a new insight into the therapeutic potential of urolithin A in the prevention and treatment of OSCC.

A Molecular Hypothesis on Malignant Transformation of Oral Lichen Planus: A Systematic Review and Meta-Analysis of Cancer Hallmarks Expression in This Oral Potentially Malignant Disorder

We aimed to qualitatively and quantitatively analyze, through a systematic review and meta-analysis, the current evidence on the differential expression of the hallmarks of cancer in oral lichen planus (OLP) samples, in order to know the earliest molecular mechanisms that could be involved in the malignant transformation of this oral potentially malignant disorder. We searched MEDLINE/PubMed, Embase, Web of Science, and Scopus for studies published before November 2023. We evaluated the methodological quality of studies and carried out meta-analyses to fulfill our objectives. Inclusion criteria were met by 110 primary-level studies, with 7065 OLP samples, in which the expression of 104 biomarkers were analyzed through immunohistochemistry. Most OLP samples showed sustained cell proliferation signaling (65.48%, 95%CI = 51.87-78.02), anti-apoptotic pathways (55.93%, 95%CI = 35.99-75.0), genome instability (48.44%, 95%CI = 13.54-84.19), and tumor-promoting inflammation events (83.10%, 95%CI = 73.93-90.74). Concurrently, OLP samples also harbored tumor growth suppressor mechanisms (64.00%, 95%CI = 53.27-74.12). In conclusion, current evidence indicates that molecular mechanisms promoting hyperproliferative signaling, an antiapoptotic state with genomic instability, and an escape of epithelial cells from immune destruction, are developed in LP-affected oral mucosa. It is plausible that these events are due to the actions exerted by the chronic inflammatory infiltrate. Malignant transformation appears to be prevented by tumor suppressor genes, which showed consistent upregulation in OLP samples.

Expression of PD-L1 and p-RPS6 in epithelial dysplasia and squamous cell carcinoma of the oral cavity

Introduction

Oral squamous cell carcinoma (OSCC) is often preceded by oral epithelial dysplasia (OED). The role of ribosomal protein S6 (RPS6) and programmed cell death ligand-1 (PD-L1) in the progression of OED to OSCC remains unclear. This study aimed to investigate the expression of phosphorylated RPS6 (p-RPS6) and PD-L1 in OSCC and OED and to examine its relationship with clinicopathological features.

Methods

Fifty-two OSCC and 48 OED cases were recruited for immunohistochemical analysis of p-RPS6 and PD-L1 expression. The expression of markers was correlated with clinicopathological features of OSCC and OED.

Results

We found p-RPS6 expression in all cases of OSCC and OED, whereas PD-L1 was expressed in 42/48 (87%) OED and in 28/52 (53%) OSCC. The patients with mild OED presented higher expression level of PD-L1 and p-RPS6 significantly, when compared to moderate-differentiated OSCC patients (p < 0.05). Moreover, we found a significant positive correlation between PD-L1 and p-RPS6 expression in OED and OSCC patients (p < 0.01). The PD-L1 expression was significantly related to more than 2 cm tumor size in OSCC patients (p = 0.007).

Discussion

Our findings suggest the upregulation of PD-L1 may be related with activation of the mTOR pathway in the early events of tumor progression and the pathogenesis of OSCC.

Melatonin Exerts Prominent, Differential Epidermal and Dermal Anti-Aging Properties in Aged Human Eyelid Skin Ex Vivo

Human skin aging is associated with functional deterioration on multiple levels of physiology, necessitating the development of effective skin senotherapeutics. The well-tolerated neurohormone melatonin unfolds anti-aging properties in vitro and in vivo, but it remains unclear whether these effects translate to aged human skin ex vivo. We tested this in organ-cultured, full-thickness human eyelid skin (5-6 donors; 49-77 years) by adding melatonin to the culture medium, followed by the assessment of core aging biomarkers via quantitative immunohistochemistry. Over 6 days, 200 µM melatonin significantly downregulated the intraepidermal activity of the aging-promoting mTORC1 pathway (as visualized by reduced S6 phosphorylation) and MMP-1 protein expression in the epidermis compared to vehicle-treated control skin. Conversely, the transmembrane collagen 17A1, a key stem cell niche matrix molecule that declines with aging, and mitochondrial markers (e.g., TFAM, MTCO-1, and VDAC/porin) were significantly upregulated. Interestingly, 100 µM melatonin also significantly increased the epidermal expression of VEGF-A protein, which is required and sufficient for inducing human skin rejuvenation. In aged human dermis, melatonin significantly increased fibrillin-1 protein expression and improved fibrillin structural organization, indicating an improved collagen and elastic fiber network. In contrast, other key aging biomarkers (SIRT-1, lamin-B1, p16INK4, collagen I) remained unchanged. This ex vivo study provides proof of principle that melatonin indeed exerts long-suspected but never conclusively demonstrated and surprisingly differential anti-aging effects in aged human epidermis and dermis.

The PI3K-Akt-mTOR and Associated Signaling Pathways as Molecular Drivers of Immune-Mediated Inflammatory Skin Diseases: Update on Therapeutic Strategy Using Natural and Synthetic Compounds

The dysregulated phosphatidylinositol-3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) signaling pathway has been implicated in various immune-mediated inflammatory and hyperproliferative dermatoses such as acne, atopic dermatitis, alopecia, psoriasis, wounds, and vitiligo, and is associated with poor treatment outcomes. Improved comprehension of the consequences of the dysregulated PI3K/Akt/mTOR pathway in patients with inflammatory dermatoses has resulted in the development of novel therapeutic approaches. Nonetheless, more studies are necessary to validate the regulatory role of this pathway and to create more effective preventive and treatment methods for a wide range of inflammatory skin diseases. Several studies have revealed that certain natural products and synthetic compounds can obstruct the expression/activity of PI3K/Akt/mTOR, underscoring their potential in managing common and persistent skin inflammatory disorders. This review summarizes recent advances in understanding the role of the activated PI3K/Akt/mTOR pathway and associated components in immune-mediated inflammatory dermatoses and discusses the potential of bioactive natural products, synthetic scaffolds, and biologic agents in their prevention and treatment. However, further research is necessary to validate the regulatory role of this pathway and develop more effective therapies for inflammatory skin disorders.

Network Pharmacology and Molecular Docking Analysis Explores the Mechanisms of Cordyceps sinensis in the Treatment of Oral Lichen Planus

Objective

Oral lichen planus (OLP) is the most common potentially malignant disorder of the oral cavity. This study aimed to investigate the mechanism of action of Cordyceps sinensis in the treatment of OLP and provides a theoretical support for improving current treatment regimens for OLP.

Methods

The active components and therapeutic targets of Cordyceps sinensis were predicted and screened using the TCMSP, SymMap, PubMed, HIT 2.0, and PharmMapper databases, while the relevant OLP targets were predicted and screened using the DisGeNET and GeneCards databases. Protein-protein interactions (PPI) were examined using the String database, and Cytoscape was used to combine and illustrate the findings. GO and KEGG pathway enrichment analyses were carried out using RStudio, and AutoDock Vina and Pymol were used for molecular docking and visualization, respectively.

Results

A total of 404 potential target genes were discovered after evaluating 21 active compounds from Cordyceps sinensis. Potential therapeutic targets included 67 targets that matched and overlapped with OLP, including TNF, IL-6, CD4, EGFR, and IL1B. Key targets were predominantly engaged in the PI3K-Akt signaling pathway and the MAPK signaling pathway, according to the GO and KEGG analyses. These targets have a connection to biological processes including apoptosis signaling pathway regulation, T cell activation, and oxidative stress response. The molecular docking results showed that TNF, IL-6, CD4, EGFR, and IL1B could bind to their corresponding active components.

Conclusions

Cordyceps sinensis contains multiple components and acts on multiple targets and multiple pathways. Particularly, Cordyceps sinensis targets TNF, IL-6, CD4, EGFR, and IL1B, regulates PI3K-Akt and MAPK signaling pathways, as well as takes part in biological processes including apoptosis, T cell activation, and oxidative stress. Cordyceps sinensis could be a crucial choice in the therapy of OLP.

Norepinephrine Leads to More Cardiopulmonary Toxicities than Epinephrine by Catecholamine Overdose in Rats

While catecholamines like epinephrine (E) and norepinephrine (NE) are commonly used in emergency medicine, limited studies have discussed the harm of exogenously induced catecholamine overdose. We investigated the possible toxic effects of excessive catecholamine administration on cardiopulmonary function and structure via continuous 6 h intravenous injection of E and/or NE in rats. Heart rate, echocardiography, and ventricular pressure were measured throughout administration. Cardiopulmonary structure was also assessed by examining heart and lung tissue. Consecutive catecholamine injections induced severe tachycardia. Echocardiography results showed NE caused worse dysfunction than E. Simultaneously, both E and NE led to higher expression of Troponin T and connexin43 in the whole ventricles, which increased further with E+NE administration. The NE and E+NE groups showed severe pulmonary edema while all catecholamine-administering groups demonstrated reduced expression of receptor for advanced glycation end products and increased connexin43 levels in lung tissue. The right ventricle was more vulnerable to catecholamine overdose than the left. Rats injected with NE had a lower survival rate than those injected with E within 6 h. Catecholamine overdose induces acute lung injuries and ventricular cardiomyopathy, and E+NE is associated with a more severe outcome. The similarities of the results between the NE and E+NE groups may indicate a predominant role of NE in determining the overall cardiopulmonary damage. The results provide important clinical insights into the pathogenesis of catecholamine storm.

mTOR Signaling Combined with Cancer Stem Cell Markers as a Survival Predictor in Stage II Colorectal Cancer

PURPOSE

Wnt and mammalian target of rapamycin (mTOR) are major molecular signaling pathways associated with the development and progression of tumor, as well as the maintenance and proliferation of cancer stem cells (CSCs), in colorectal cancer (CRC). Identifying patients at risk of poor prognosis is important to determining whether to add adjuvant treatment in stage II CRC and thus improve survival. In the present study, we evaluated the prognostic value of Wnt, mTOR, and CSC markers as survival predictors in stage II CRC.

MATERIALS AND METHODS

We identified 148 cases of stage II CRC and acquired their tumor tissue. Tissue microarrays for immunohistochemical staining were constructed, and the expressions of CD166, CD44, EphB2, β-catenin, pS6 were evaluated using immunohistochemical staining.

RESULTS

The expressions of CD166 (p=0.045) and pS6 (p=0.045) and co-expression of pS6/CD166 (p=0.005), pS6/CD44 (p=0.042), and pS6/CD44/CD166 (p=0.013) were negatively correlated with cancer-specific survival. Cox proportional hazard analysis showed the combination of CD166/pS6 [hazard ratio, 9.42; 95% confidence interval, 2.36-37.59; p=0.002] to be the most significant predictor related with decreased cancer-specific survival. In addition, co-expression of CD44/CD166 (p=0.017), CD166/β-catenin (p=0.036), CD44/β-catenin (p=0.001), and CD44/CD166/β-catenin (p=0.001) were significant factors associated with liver metastasis.

CONCLUSION

Specific combinations of CSC markers and β-catenin/mTOR signaling could be a significant predictor of poor survival in stage II CRC.

Genipin Induces Autophagy and Suppresses Cell Growth of Oral Squamous Cell Carcinoma via PI3K/AKT/MTOR Pathway

Background

Oral squamous cell carcinoma (OSCC) is a common malignant tumor of the head and neck, and it accounts for more than 90% of oral cancer. Due to high mortality, limitations of traditional treatment and many complications, new treatment methods are urgently needed. This study aimed to look into the effect of new potential anti-tumor drug, genipin, on OSCC treatment.

Methods

In vitro, CCK-8, colony formation, and flow cytometry were used to detect the effect of genipin on SCC-9 and SCC-15 cell lines. Immunofluorescence, real-time PCR, and Western blotting were used to investigate its mechanism. Xenograft tumor model was used to explore the role of genipin in vivo.

Results

We found that genipin suppressed cell growth and induced apoptosis in vitro. In addition, the expression of p62 was down-regulated while Beclin1 and LC3II were up-regulated in SCC-25 and SCC-9 cells. 3-methyladenine (3-MA) significantly decreased LC3 (LC3II)⁺ puncta, but genipin rescuect 3d this reduction. Furthermore, genipin also reduced the expression of p-PI3K, p-AKT, and p-mTOR. In vivo experiment showed that genipin significantly curbed the tumor size and weight. The positive expression of Ki67 protein and number of apoptotic cells were increased.

Conclusion

Conclusively, this study implicated that genipin suppresses cell proliferation and stimulated apoptosis, and is the first exploration showing that genipin induces OSCC cell autophagy via PI3K/AKT/mTOR pathway inhibition.

miR‑122 and miR‑199 synergistically promote autophagy in oral lichen planus by targeting the Akt/mTOR pathway

The aim of the present study was to characterize the roles of two microRNAs (miRNAs), miR-122 and miR-199, in oral lichen planus (OLP). miRNA microarray analysis was performed to detect potential miRNAs involved in OLP, while in-silicon analysis, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), western blot and immunohistochemistry (IHC) analyses were utilized to explore the molecular mechanisms underlying the roles of miR-199 and miR-122 in OLP. The results from the microarray and RT-qPCR analyses demonstrated that the expression levels of miR-122 and miR-199 were significantly decreased in the peripheral blood mononuclear cells (PBMCs) collected from the OLP group compared with the control group. In addition, miR-122 and miR-199 directly targeted AKT serine/threonine kinase 1 (AKT1) and mammalian target of rapamycin (mTOR), respectively, by binding to their 3′ UTRs. AKT1 and mTOR were highly expressed in PBMCs derived from OLP patients. In fact, a negative regulatory relationship was observed between miR-122 and AKT1, and between miR-199 and mTOR, with negative correlation coefficients of −0.41 and −0.51, respectively. Furthermore, the protein levels of AKT1, mTOR and microtubule associated protein 1 light chain 3β (LC3B) were upregulated in the OLP group compared with the control group. Finally, overexpression of miR-122 inhibited the expression of AKT1 and LC3B, while overexpression of miR-199 reduced the levels of mTOR and LC3B. In conclusion, the present study demonstrated that miR-199 and miR-122 are implicated in the pathogenesis of OLP by regulating the expression of mTOR and AKT1.

Differentially circulating exosomal microRNAs expression profiling in oral lichen planus

Oral lichen planus (OLP) is a common chronic inflammatory autoimmune disease with unclear etiology. The aim of the present study was to identify the expression profiles of circulating exosomal miRNAs, which have been shown to be potent stimulators of inflammatory and immune responses, in OLP patients. Plasma exosomes were isolated from the patients and healthy individuals, and RAE scoring system was used to evaluate the severity of OLP. Differentially deregulated exosomal miRNAs associated with inflammatory response and autoimmunity in OLP were identified by miScript^® miRNA PCR Array, and the results were confirmed by RT-PCR. The relationship between exosomal miRNAs and RAE scores was then analyzed, and bioinformatics analysis was used to predict the target genes and pathways of the differentially expressed exosomal miRNAs. Expression profiling showed that circulating exosomal miR-34a-5p and miR-130b-3p were upregulated, while miR-301b-3p was downregulated in OLP patients. Exosomal miR-34a-5p was positively correlated with the severity of OLP. Bioinformatics analysis revealed that the target genes of miR-34a-5p were mainly involved in regulation of gene expression, cell communication, signaling, and metabolic process, and modulated OLP progression through the PI3K/Akt signaling pathway. In conclusion, circulating exosomal miR-34a-5p could be a potential biomarker for evaluating the severity of OLP.

Expression of Vascular Endothelial-Cadherin in Mucoepidermoid Carcinoma: Role in Cancer Development

Objectives:

Mucoepidermoid carcinoma (MEC) accounts for 35% of all malignant salivary gland tumors. Previous investigations have shown that vasculogenic mimicry (VM) exists in many cancers which can be used as a prognostic factor of poor prognosis. Elevated expression level of vascular endothelial (VE)-cadherin has been implicated in cancer neovascularization, growth, and progression. The current study aimed to study the presence of VE-cadherin in VM channels and tumor cells in different grades of MEC.

Materials and Methods:

A total of 63 MEC samples (21 samples in each grade) were collected from the archive of pathology department of Besat Educational Hospital, Hamadan, Iran, from 2002 to 2016. Hematoxylin and eosin staining was performed to confirm the previous diagnosis. The specimens were then processed for immunohistochemistry analysis. Then, periodic acid–Schiff staining was performed. Analyses were conducted through SPSS software version 22.0 (SPSS, Inc., Chicago, IL, USA). Chi-square test was used to examine the differences between categorical variables. Significance level was set at 0.05. Pearson's correlation was used to assess the co-localization of the marker.

Results:

A total of 63 samples (35 men; 55.6%, and 28 women; 44.4%) were used for immunohistochemical study. There were statistically significant differences between tumor grade and the expression levels of VE-cadherin (P = 0.000), between tumor grade and VM formation (P = 0.000), and also between tumor grade and microvessel density (MVD) (P = 0.000). Additionally, there was a strong positive correlation between tumor grade and VE-cadherin expression level (Pearson's r = 0.875, P < 0.000).

Conclusions:

Our results may disclose a definite relationship between VE-cadherin expression level, VM, epithelial–mesenchymal transition, cancer stem cells, and MVD in MEC samples. Thus, it is reasonable to suggest that VE-cadherin is related to angiogenesis and VM formation in MECs.

Immunohistochemical evaluation of the mTOR pathway in intra-oral minor salivary gland neoplasms

OBJECTIVES

The aim of this study was to investigate the expression of upstream and downstream molecules of the oncogenic mTOR signaling pathway in intra-oral minor salivary gland tumors (SGTs).

MATERIALS AND METHODS

Tissue samples consisted of 39 malignant and 13 benign minor SGTs, and 8 controls of normal minor salivary glands (NMSG). An immunohistochemical analysis for phosphorylated Akt, 4EBP1 and S6 (total and phosphorylated), and eIF4E was performed.

RESULTS

Expression of pAkt and 4EBP1 was observed in all SGTs and in most NMSG. p4EBP1 was detected in almost all SGT cases, NMSG being negative. S6 immunoreactivity was observed in 37.5% of NMSG, 92.3% of benign and 100% of malignant SGTs, while pS6 expression was observed in 77% of benign and 95% of malignant SGTs, but not in NMSG. Finally, eIF4E was expressed in 12.5% of NMSG, 69.2% of benign, and 76.9% of malignant tumors. All molecules studied had statistically significantly lower expression in NMSG compared with SGTs. Moreover, malignant neoplasms received higher scores compared with benign tumors for all molecules with the exception of eIF4E.

CONCLUSION

The mTOR signaling pathway is activated in SGTs, especially in malignancies. Therefore, the possible therapeutic role of targeting the mTOR pathway by rapamycin analogs in SGTs needs further investigation.

[Immunomorphology of oral lichen planus]

The article is devoted to immunohistochemical study of reticular and erosive forms of oral lichen planus. Morphological examination of the reticular form revealed the increased number of Langerhans cells (CD1a), mast cells (CD25) and T lymphocytes (CD4, CD8, CD16) in the oral epithelium. Activation of these cells leads to the secretion of TNF-α and destruction of basal keratinocytes, which manifests as a focal reduction of intercellular protein expression of E-cadherin. Destruction of basal keratinocytes in a reticular form of oral lichen planus is accompanied by a significant decrease in proliferative activity of the basal cell layer (21.7±10.2%) compared with normal mucosa (33.6±7.0%), p=0.0045. In erosive form along with the above changes IgG and C3d complement's elements are revealed, which confirms the activation of immune complex mechanisms in the erosion area.

Biomarker and Pathologic Predictors of Cutaneous Squamous Cell Carcinoma Aggressiveness

OBJECTIVE

Aggressive cutaneous squamous cell carcinoma (cSCC) patients are at increased risk of metastasis. Currently, there are no accepted criteria or biomarkers for reliably predicting individuals at risk for recurrence and metastasis. Our objective is to determine if pS6 and pERK can predict cSCC aggressiveness and to identify primary tumor characteristics that may predict parotid metastasis.

STUDY DESIGN

Retrospective case series.

SETTINGS

Tertiary care center.

SUBJECTS AND METHODS

An Institutional Review Board-approved retrospective review was performed for patients with facial cSCC, with and without metastasis to the parotids. Subjects for the study were identified through the Louisiana Tumor Registry, Veterans Medical Records, and LSU Health-Shreveport pathology database. Tumor specimens from patients with cSCC and cSCC with parotid metastasis were analyzed for pERK and pS6 expression through immunohistochemistry. To identify risk factors for tumor aggressiveness, multiple logistic regression analysis was used to evaluate patients with cSCC that was metastatic to the parotid and managed surgically.

RESULTS

cSCC with parotid metastasis specimens exhibited significantly higher average pS6 but not pERK positivity than those from cSCC without metastasis (P < .05). Primary lesion-positive margins (P < .01), size of the skin tumor (P < .01) and degree of tumor differentiation (P < .01) were significantly associated with parotid metastasis.

CONCLUSION

Surgical history of cSCC, primary lesion-positive margins, degree of differentiation, and lesion size together with pS6 positivity appear to be predictors of cSCC aggressiveness and should prompt increased monitoring or elective parotidectomy.

miR-125b inhibits keratinocyte proliferation and promotes keratinocyte apoptosis in oral lichen planus by targeting MMP-2 expression through PI3K/Akt/mTOR pathway

Oral lichen planus (OLP) is a chronic inflammatory mucosal disease that involves the degeneration of keratinocytes. However, the etiology and mechanisms of OLP pathogenesis have not been fully elucidated. In this study, we used keratinocytes HaCaT stimulated with lipopolysaccharide (LPS) to mimic a local OLP immune environment, and investigated the regulatory role of miR-125b in keratinocyte proliferation and apoptosis under OLP conditions. Immunohistochemical analysis and quantitative real-time PCR (qRT-PCR) assay showed that MMP-2 expression was up-regulated and miR-125b expression was down-regulated in both OLP mucosa tissues and LPS-incubated HaCaT cells. Western blot analysis indicated that miR-125b overexpression suppressed LPS-induced MMP-2 expression in HaCaT cells. Molecularly, our results confirmed that MMP-2 is a target gene of miR-125b in HaCaT cells. The effect of miR-125b on cell proliferation was revealed by CCK-8 assay, BrdU assay and cell cycle analysis, which illustrated that miR-125b overexpression impeded LPS-induced HaCaT cell proliferation. Flow cytometry analysis further demonstrated that miR-125b overexpression promoted HaCaT cell apoptosis. Moreover, these effects were involved in PI3K/Akt/mTOR activation, as miR-125b overexpression inhibited LPS-enhanced expression of p-Akt and p-mTOR proteins. Taken together, these data confirm that miR-125b might inhibit keratinocyte proliferation and promote keratinocyte apoptosis in OLP pathogenesis by targeting MMP-2 through PI3K/Akt/mTOR pathway.

Could the PI3K canonical pathway be a common link between chronic inflammatory conditions and oral carcinogenesis?

The association between chronic inflammatory disorders and oral carcinogenesis has been both a source of interest and contention. Based upon its central importance in oral carcinogenesis, the finding that the PI3k/Akt/mTOR pathway is activated in oral lichen planus, chronic graft-versus-host disease, and chronic oral candidiasis suggests that it may provide a link between benign and malignant oral conditions. Here, we discuss a possible mechanistic rationale that addresses the activation of this important signaling pathway and its downstream events, while correlating it with the carcinogenic potential of chronic oral disorders.

PI3K-AKT-mTOR pathway proteins are differently expressed in oral carcinogenesis

BACKGROUND

PI3K-AKT-mTOR signaling pathway is associated with several cellular functions and is frequently changed in several malignancies. The aim of this study was to characterize the immunohistochemical expression pattern of components in PI3K-AKT-mTOR signaling pathway in oral epithelial dysplasia (OED), comparing to oral squamous cell carcinoma (OSCC) and non-dysplastic oral tissues (NDOT).

METHODS

A total of 186 cases of NDOT, OED and OSCC were retrieved. Nuclear staining and cytoplasmic staining of the keratinocytes were considered positive, and the percentage of positive cells was calculated.

RESULTS

Increased immunoreactivity from NDOT to OED and OSCC was seen for all proteins. In NDOT cases, positivity was found only for pS6 (52.9%) and p4EBP1 (13.5%). In OED, immunoreactivity was observed for pAKT (62.2%), pmTOR (28.6%), pS6 (70.8%), and p4EBP1 (42.9%). In OSCC cases, immunoreactivity was found for pAKT (83.3%), pmTOR (50%), pS6 (77.4%), and p4EBP1 (50%). The pAKT and pmTOR expression was higher in OED (<0.001, Fisher's exact test) and OSCC (<0.001, Fisher's exact test).

CONCLUSION

Our study demonstrated higher pAKT and pmTOR expression during carcinogenesis of oral mucosa, differing considerably among OED and OSCC specimens when compared to NDOT. These proteins can be considered potential diagnostic markers for early detection of cancer.