Expression of phosphorylated Akt in oral carcinogenesis and its induction by nicotine and alkaline stimulation

Effect of the Protein Kinase B (PKB) Gene on the Carcinogenesis of Oral Squamous Cell Carcinoma in the South Indian Population

INTRODUCTION

The most common head and neck cancer is oral squamous cell carcinoma (OSCC). It is also one of the most prevalent forms of cancer globally. The current pharmacological treatment strategy for oral cancer lacks specificity and is capable of causing various side effects. This fact highlights the increasing need for targeted therapy. Interestingly, protein kinase B (PKB), commonly referred to as the AKT serine/threonine kinase, is an oncogenic protein that controls cell development, proliferation, apoptosis, and glycogen metabolism. Thus, the present study analyzed the AKT gene expression in OSCC patient samples.

MATERIALS AND METHODS

A total of 25 OSCC tissue samples and normal tissue samples were collected from the patients who reported to the Department of Oral and Maxillofacial Surgery, Saveetha Dental College and Hospitals in Chennai, India. The tissues were processed for H&E staining for histopathological confirmation, and expression studies of the AKT gene were done on both healthy and proven OSCC tissue samples. The data were shown as mean ± standard deviation, and p<0.05* was considered to be statistically significant.

RESULTS

The quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis revealed that the AKT gene had been significantly upregulated in the OSCC tissue samples when compared to normal tissues (p<0.05). Moreover, upregulated AKT is postulated to be involved in increased cell proliferation and reduced apoptosis in OSCC.

CONCLUSION

The gene expression analysis was done in the samples of histologically confirmed OSCC, and it revealed that the AKT gene was significantly upregulated in OSCC tissues. Thus, AKT could be postulated as a potential therapeutic target for OSCC.

Role of Akt/Protein Kinase B in Cancer Metastasis

Metastasis is a critical step in the process of carcinogenesis and a vast majority of cancer-related mortalities result from metastatic disease that is resistant to current therapies. Cell migration and invasion are the first steps of the metastasis process, which mainly occurs by two important biological mechanisms, i.e., cytoskeletal remodelling and epithelial to mesenchymal transition (EMT). Akt (also known as protein kinase B) is a central signalling molecule of the PI3K-Akt signalling pathway. Aberrant activation of this pathway has been identified in a wide range of cancers. Several studies have revealed that Akt actively engages with the migratory process in motile cells, including metastatic cancer cells. The downstream signalling mechanism of Akt in cell migration depends upon the tumour type, sites, and intracellular localisation of activated Akt. In this review, we focus on the role of Akt in the regulation of two events that control cell migration and invasion in various cancers including head and neck squamous cell carcinoma (HNSCC) and the status of PI3K-Akt pathway inhibitors in clinical trials in metastatic cancers.

SOD2 Enhancement by Long-Term Inhibition of the PI3K Pathway Confers Multi-Drug Resistance and Enhanced Tumor-Initiating Features in Head and Neck Cancer

The phosphoinositide-3-kinase (PI3K) pathway has widely been considered as a potential therapeutic target for head and neck cancer (HNC); however, the application of PI3K inhibitors is often overshadowed by the induction of drug resistance with unknown mechanisms. In this study, PII3K inhibitor resistant cancer cells were developed by prolonged culturing of cell lines with BEZ235, a dual PI3K and mammalian target of rapamycin (mTOR) inhibitor. The drug resistant HNC cells showed higher IC₅₀ of the proliferation to inhibitors specifically targeting PI3K and/or mTOR, as compared to their parental cells. These cells also showed profound resistance to drugs of other classes. Molecular analysis revealed persistent activation of phosphorylated AKT at threonine 308 in the drug resistant cells and increased expression of markers for tumor-initiating cells. Interestingly, increased intra-cellular ROS levels were observed in the drug resistant cells. Among anti-oxidant molecules, the expression of SOD2 was increased and was associated with the ALDH-positive tumor-initiating cell features. Co-incubation of SOD inhibitors and BEZ235 decreased the stemness feature of the cells in vitro, as shown by results of the spheroid formation assay. In conclusion, dysregulation of SOD2 might contribute to the profound resistance to PI3K inhibitors and the other drugs in HNC cells.

Targeting AKT/mTOR in Oral Cancer: Mechanisms and Advances in Clinical Trials

Oral cancer (OC) is a devastating disease that takes the lives of lots of people globally every year. The current spectrum of treatment modalities does not meet the needs of the patients. The disease heterogeneity demands personalized medicine or targeted therapies. Therefore, there is an urgent need to identify potential targets for the treatment of OC. Abundant evidence has suggested that the components of the protein kinase B (AKT)/ mammalian target of rapamycin (mTOR) pathway are intrinsic factors for carcinogenesis. The AKT protein is central to the proliferation and survival of normal and cancer cells, and its downstream protein, mTOR, also plays an indispensable role in the cellular processes. The wide involvement of the AKT/mTOR pathway has been noted in oral squamous cell carcinoma (OSCC). This axis significantly regulates the various hallmarks of cancer, like proliferation, survival, angiogenesis, invasion, metastasis, autophagy, and epithelial-to-mesenchymal transition (EMT). Activated AKT/mTOR signaling is also associated with circadian signaling, chemoresistance and radio-resistance in OC cells. Several miRNAs, circRNAs and lncRNAs also modulate this pathway. The association of this axis with the process of tumorigenesis has culminated in the identification of its specific inhibitors for the prevention and treatment of OC. In this review, we discussed the significance of AKT/mTOR signaling in OC and its potential as a therapeutic target for the management of OC. This article also provided an update on several AKT/mTOR inhibitors that emerged as promising candidates for therapeutic interventions against OC/head and neck cancer (HNC) in clinical studies.

Stimulation of MMP-9 of oral epithelial cells by areca nut extract is related to TGF-β/Smad2-dependent and -independent pathways and prevented by betel leaf extract, hydroxychavicol and melatonin

BACKGROUND

There are 200-600 million betel quid (BQ) chewers in the world. BQ increases oral cancer risk. Matrix metalloproteinase-9 (MMP-9) is responsible for matrix degradation, cancer invasion and metastasis. Whether areca nut extract (ANE), a BQ component, stimulates MMP-9 secretion, and the related signaling pathways awaits investigation.

RESULTS

ANE (but not arecoline) stimulated MMP-9 production of gingival keratinocytes and SAS cancer epithelial cells. ANE stimulated TGF-β1, p-Smad2, and p-TAK1 protein expression. ANE-induced MMP-9 production/expression in SAS cells can be attenuated by SB431542 (ALK5/Smad2 inhibitor), 5Z-7-Oxozeaenol (TAK1 inhibitor), catalase, PD153035 (EGFR tyrosine kinase inhibitor), AG490 (JAK inhibitor), U0126 (MEK/ERK inhibitor), LY294002 (PI3K/Akt inhibitor), betel leaf (PBL) extract, and hydroxychavicol (HC, a PBL component), and melatonin, but not by aspirin.

CONCLUSIONS

AN components contribute to oral carcinogenesis by stimulating MMP-9 secretion, thus enhancing tumor invasion/metastasis. These events are related to reactive oxygen species, TGF-β1, Smad2-dependent and -independent signaling, but not COX. These signaling molecules can be biomarkers of BQ carcinogenesis. PBL, HC and melatonin and other targeting therapy can be used for oral cancer treatment.

METHODS

ANE-induced MMP-9 expression/secretion of oral epithelial cells and related TGF-β1, Smad-dependent and -independent signaling were studied by MTT assay, RT-PCR, western blotting, immunofluorescent staining, and ELISA.

Pathologic significance of AKT, mTOR, and GSK3β proteins in oral squamous cell carcinoma-affected patients

Phosphatidylinositol-3-kinases are kinases that lead to AKT phosphorylation and thus mTOR and GSK3β activation. These proteins are linked to tumorigenesis, but their roles in driving cervical lymph node (CLN) metastasis of oral squamous cell carcinoma (OSCC) cells are unknown. This study aimed to investigate the role of AKT, mTOR, and GSK3β proteins in the occurrence of CLN metastasis in OSCC patients. Ninety and 18 paraffin-embedded OSCC and oral mucosa samples were included, respectively. We divided our OSCC patients into non-metastasizing (PNM) and metastasizing (PM) groups, and the expression of total AKT, pAKT1^Thr308, pAKT^Ser473, GSK3β, pGSK3β^Ser9, and pmTOR^Ser2448 was analyzed by immunohistochemistry. The mean expression of GSK3β, pGSK3β^Ser9, total AKT, and pmTOR²⁴⁴⁸ was always higher in the OSCC tissues than that in the controls. A positive correlation was also found among these proteins. Total AKT, pmTOR^Ser2448, and pGSK3β^Ser9 expression was significantly higher in the PNM and PM groups than that in the control group. However, only GSK3β expression was significantly higher in the PM group compared with the PNM group. High expression levels of GSK3β and pGSK3β^Ser9 were significantly associated with CLN metastasis, but only GSK3β remained an independent predictor of CLN metastasis. pGSK3β^Ser9 and CLN metastasis were associated with a poor prognosis, but only the latter remained an independent prognostic parameter. Kaplan-Meier survival curves showed that pGSK3β^Ser9 and CLN metastasis were significantly related to reduced survival rates. These results suggest that AKT and mTOR proteins are involved in OSCC biology and that GSK3β itself may drive CLN metastatic spread of OSCC cells.

Melatonin Inhibits Reactive Oxygen Species-Driven Proliferation, Epithelial-Mesenchymal Transition, and Vasculogenic Mimicry in Oral Cancer

Globally, oral cancer is the most common type of head and neck cancers. Melatonin elicits inhibitory effects on oral cancer; however, the biological function of melatonin and underlying mechanisms remain largely unknown. In this study, we found that melatonin impaired the proliferation and apoptosis resistance of oral cancer cells by inactivating ROS-dependent Akt signaling, involving in downregulation of cyclin D1, PCNA, and Bcl-2 and upregulation of Bax. Melatonin inhibited the migration and invasion of oral cancer cells by repressing ROS-activated Akt signaling, implicating with the reduction of Snail and Vimentin and the enhancement of E-cadherin. Moreover, melatonin hampered vasculogenic mimicry of oral cancer cells through blockage of ROS-activated extracellular-regulated protein kinases (ERKs) and Akt pathways involving the hypoxia-inducible factor 1α. Consistently, melatonin retarded tumorigenesis of oral cancer in vivo. Overall, these findings indicated that melatonin exerts antisurvival, antimotility, and antiangiogenesis effects on oral cancer partly by suppressing ROS-reliant Akt or ERK signaling.

SOX2 and PI3K Cooperate to Induce and Stabilize a Squamous-Committed Stem Cell Injury State during Lung Squamous Cell Carcinoma Pathogenesis

Although cancers are considered stem cell diseases, mechanisms involving stem cell alterations are poorly understood. Squamous cell carcinoma (SQCC) is the second most common lung cancer, and its pathogenesis appears to hinge on changes in the stem cell behavior of basal cells in the bronchial airways. Basal cells are normally quiescent and differentiate into mucociliary epithelia. Smoking triggers a hyperproliferative response resulting in progressive premalignant epithelial changes ranging from squamous metaplasia to dysplasia. These changes can regress naturally, even with chronic smoking. However, for unknown reasons, dysplasias have higher progression rates than earlier stages. We used primary human tracheobronchial basal cells to investigate how copy number gains in SOX2 and PIK3CA at 3q26-28, which co-occur in dysplasia and are observed in 94% of SQCCs, may promote progression. We find that SOX2 cooperates with PI3K signaling, which is activated by smoking, to initiate the squamous injury response in basal cells. This response involves SOX9 repression, and, accordingly, SOX2 and PI3K signaling levels are high during dysplasia, while SOX9 is not expressed. By contrast, during regeneration of mucociliary epithelia, PI3K signaling is low and basal cells transiently enter a SOX2LoSOX9Hi state, with SOX9 promoting proliferation and preventing squamous differentiation. Transient reduction in SOX2 is necessary for ciliogenesis, although SOX2 expression later rises and drives mucinous differentiation, as SOX9 levels decline. Frequent coamplification of SOX2 and PIK3CA in dysplasia may, thus, promote progression by locking basal cells in a SOX2HiSOX9Lo state with active PI3K signaling, which sustains the squamous injury response while precluding normal mucociliary differentiation. Surprisingly, we find that, although later in invasive carcinoma SOX9 is generally expressed at low levels, its expression is higher in a subset of SQCCs with less squamous identity and worse clinical outcome. We propose that early pathogenesis of most SQCCs involves stabilization of the squamous injury state in stem cells through copy number gains at 3q, with the pro-proliferative activity of SOX9 possibly being exploited in a subset of SQCCs in later stages.

Asiatic Acid Attenuates Myocardial Ischemia/Reperfusion Injury via Akt/GSK-3β/HIF-1α Signaling in Rat H9c2 Cardiomyocytes

Myocardial ischemic/reperfusion injury results from severe impairment of coronary blood supply and leads to irreversible cell death, with limited therapeutic possibilities. Asiatic acid is a pentacyclic triterpenoid derived from the tropical medicinal plant Centella asiatica and serves a variety of bioactivities. In this study, we determined the effect of asiatic acid on myocardial ischemia/reperfusion injury and investigated the underlying mechanisms, using an in vitro rat H9c2 cardiomyocytes model of oxygen-glucose deprivation/reoxygenation (OGD/R) injury. Results showed that pre-treatment with asiatic acid significantly augmented cell viability and prevented lactate dehydrogenase (LDH) release in a concentration-dependent manner after OGD/R exposure. Asiatic acid at 10 μM effectively inhibited apoptotic cell death, suppressed the activities of caspase-3 and caspase-9, and reversed Bax/Bcl-2 ratio in hypoxic H9c2 cells. In addition, asiatic acid improved mitochondrial function, as evidenced by reduced reactive oxygen species (ROS) accumulation, enhanced mitochondrial membrane potential and decreased intracellular calcium concentration. Using Western blot assay, we found that asiatic acid promoted the phosphorylation of Akt and subsequent inactivation of glycogen synthase kinase-3β (GSK-3β), and induced the expression of hypoxia-inducible factor 1α (HIF-1α) after OGD/R. The cardioprotective effects of asiatic acid were attenuated by the Akt or HIF-1α inhibitor. Taken together, these data suggested that asiatic acid exerted protective effects against OGD/R-induced apoptosis in cardiomyocytes, at least partly via the Akt/GSK-3β/HIF-1α pathway.

Areca Nut Chewing and an Impaired Estimated Glomerular Filtration Rate as Significant Risk Factors for Non-Muscle-Invasive Bladder Cancer Recurrence

The present study sought to investigate the predictive value of preoperative clinicopathological variables, with a special focus on areca nut chewing, on disease recurrence and progression in patients with non-muscle-invasive bladder cancer (NMIBC). Data from 242 patients diagnosed with NMIBC between 2008 and 2013 were analyzed retrospectively. Fifteen clinicopathological variables were analyzed to evaluate their prognostic value. During a mean observation period of 21 months, disease recurrence occurred in 140 patients (57.9%). On multivariate analysis, heavy-areca nut chewing (HR = 2.18, 95% CI: 1.37-3.47), current smoking (HR = 3.09, 95% CI: 1.99-4.80), moderately impaired estimated glomerular filtration rate (eGFR) (HR = 1.76, 95% CI: 1.09-2.83), severely impaired eGFR (HR = 3.32, 95% CI: 1.70-6.48) and tumor grade (HR = 1.94, 95% CI: 1.36-2.77) were independent factors for recurrence, based on which a risk factor model was developed to stratify patients into high, medium and low risk groups. In conclusion, our study suggests that in addition to quitting smoking, quitting areca nut chewing may also reduce the risk of first recurrence in NMBIC patients, monitoring and preserving their renal function may be beneficial as well. Further prospective studies are needed to verify the prognostic significance of these factors and the risk stratification model in this population.

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.

Inhibition of Tanshinone IIA, salvianolic acid A and salvianolic acid B on Areca nut extract-induced oral submucous fibrosis in vitro

Salvia miltiorrhiza Bunge has been reported to possess excellent antifibrotic activity. In this study, we have investigated the effect and mechanism of tanshinone IIA (Tan-IIA), salvianolic acid A (Sal-A) and salvianolic acid B (Sal-B), the important active compounds of Salvia miltiorrhiza Bunge, on areca nut extract (ANE)-induced oral submucous fibrosis (OSF) in vitro. Through human procollagen gene promoter luciferase reporter plasmid assay, hydroxyproline assay, gelatin zymography assay, qRT-PCR, ELISA and Western blot assay, the influence of these three compounds on ANE-stimulated cell viability, collagen accumulation, procollagen gene transcription, MMP-2/-9 activity, MMP-1/-13 and TIMP-1/-2 expression, cytokine secretion and the activation of PI3K/AKT, ERK/JNK/p38 MAPK and TGF-β/Smads pathways were detected. The results showed that Tan-IIA, Sal-A and Sal-B could significantly inhibit the ANE-stimulated abnormal viability and collagen accumulation of mice oral mucosal fibroblasts (MOMFs), inhibit the transcription of procollagen gene COL1A1 and COL3A1, increase MMP-2/-9 activity, decrease TIMP-1/-2 expression and inhibit the transcription and release of CTGF, TGF-β1, IL-6 and TNF-α; Tan-IIA, Sal-A and Sal-B also inhibited the ANE-induced activation of AKT and ERK MAPK pathways in MOMFs and the activation of TGF-β/Smads pathway in HaCaT cells. In conclusion, Tan-IIA, Sal-A and Sal-B possess excellent antifibrotic activity in vitro and can possibly be used to promote the rehabilitation of OSF patients.

Inactivation of GSK3β and activation of NF-κB pathway via Axl represents an important mediator of tumorigenesis in esophageal squamous cell carcinoma

Deregulation of Axl in esophageal squamous cell carcinoma (OSCC) with potential therapeutic implications is described for the first time. This paper also sheds light on the understanding of how Axl regulates OSCC development in vitro and in vivo. Axl expression leads to an Akt-dependent regulation of glycogen synthase kinase 3β activity and the nucluear factor kappaB (NF-κB) pathway, affecting the epithelial–mesenchymal transition.

The receptor tyrosine kinase Axl has been described as an oncogene, and its deregulation has been implicated in the progression of several human cancers. While the role of Axl in esophageal adenocarcinoma has been addressed, there is no information about its role in esophageal squamous cell carcinoma (OSCC). In the current report, we identified, for the first time, deregulation of Axl expression in OSCC. Axl is consistently overexpressed in OSCC cell lines and human tumor samples, mainly in advanced stages of the disease. Blockage of Axl gene expression by small interfering RNA inhibits cell survival, proliferation, migration, and invasion in vitro and esophageal tumor growth in vivo. Additionally, repression of Axl expression results in Akt-dependent inhibition of pivotal genes involved in the nuclear factor-kappaB (NF-κB) pathway and in the induction of glycogen synthase kinase 3β (GSK3β) activity, resulting in loss of mesenchymal markers and induction of epithelial markers. Furthermore, treatment of esophageal cancer cells with the Akt inhibitor wortmannin inhibits NF-κB signaling, induces GSK3β activity, and blocks OSCC cell proliferation in an Axl-dependent manner. Taken together, our results establish a clear role for Axl in OSCC tumorigenesis with potential therapeutic implications.

Panax notoginseng saponins inhibit areca nut extract-induced oral submucous fibrosis in vitro

BACKGROUND

Oral submucous fibrosis (OSF) is a premalignant and fibrosing disease, which is closely associated with the habit of chewing areca nut. Panax notoginseng Buck F. H. Chen is an often used antifibrotic and antitumor agent. To treat areca nut-induced OSF, we have developed a chewable tablet, in which one of the major medicines is total Panax notoginseng saponins (PNS). In this study, we have investigated the antifibrotic effect and mechanism of PNS on areca nut-induced OSF in vitro.

METHODS

Through human procollagen gene promoter luciferase reporter plasmid, hydroxyproline assay, gelatin zymography, qRT-PCR, ELISA, and Western blot, the influences of PNS on areca nut extract (ANE)-induced cell growth, collagen accumulation, procollagen gene transcription, MMP-2/-9 activity, MMP-1/-13 and TIMP-1/-2 expression, cytokine secretion, and the activation of PI3K/AKT, ERK/JNK/p38 MAPK, and TGFβ/Smads pathways were detected.

RESULTS

Panax notoginseng saponins could inhibit the ANE-induced abnormal growth and collagen accumulation of oral mucosal fibroblasts in a concentration-dependent manner. PNS (25 μg/ml) could significantly inhibit the ANE-induced expression of Col1A1 and Col3A1, augment the ANE-induced decrease of MMP-2/-9 activity, inhibit the ANE-induced increase of TIMP-1/-2 expression, and decrease the ANE-induced transcription and release of CTGF, TGFβ1, IL-6, and TNFα. PNS (25 μg/ml) also significantly inhibited the ANE-induced activation of AKT and ERK/JNK/p38 MAPK pathways in oral mucosal fibroblasts and the ANE-induced activation of TGFβ/smad pathway in HaCaT cells.

CONCLUSION

Panax notoginseng saponins possess excellent anti-OSF activity, and its mechanism may be related to its ability to inhibit the ANE-induced activation of PI3K/AKT, ERK/JNK/p38 MAPK, and TGFβ/smad pathways.

Is there a pAkt between VEGF and oral cancer cell migration?

The PI3K-Akt signalling pathway is a well-established driver of cancer progression. One key process promoted by Akt phosphorylation is tumour cell motility; however the mechanism of VEGF-induced Akt phosphorylation leading to motility remains poorly understood. Previously, we have shown that Akt phosphorylation induced by different factors causes both stimulation and inhibition of motility in different cell types. However, differential phosphorylation of Akt at T308 and S473 residues by VEGF and its role in head and neck cancer cell motility and progression is unknown. The cell lines investigated in this study exhibited a change in phosphorylation of Akt in response to VEGF. However, in terms of motility, VEGF stimulated oral cancer and its associated cell lines, but not normal keratinocytes or oral mucosal fibroblasts. The addition of a PI3 kinase and mTOR inhibitor, inhibited the phosphorylation of Akt and also effectively blocked VEGF-induced oral cancer cell motility, whereas only the PI3 kinase inhibitor blocked oral cancer associated fibroblast cell motility. This study therefore discloses that two different mechanisms of Akt phosphorylation control the motility potential of different cell lines. Akt phosphorylated at both residues controls oral cancer cell motility. Furthermore, immunohistochemical analysis of VEGF positive human head and neck tumour tissues showed a significant increase in Akt phosphorylation at the T308 residue, suggesting that pAkt T308 may be associated with tumour progression in vivo.

GSK3β negatively regulates HIF1α mRNA stability via nucleolin in the MG63 osteosarcoma cell line

Hypoxia-inducible factor 1α (HIF1α) is a transcription factor involved in the growth, invasion and metastasis of malignant tumors. Glycogen synthase kinase 3 beta (GSK3β) is a protein kinase involved in a variety of signaling pathways, such as the Wnt and NF-κB pathways; this kinase can affect tumor progress through the regulation of transcription factor expression and apoptosis. Recent studies showed that GSK3β was involved in the expression of HIF1α. However, the effect of GSK3β on HIF1α expression in osteosarcoma cells remains unknown. To understand the relationship between GSK3β and HIF1α comprehensively, small RNA interference techniques, Western blot analyses, quantitative real-time PCR analyses and luciferase assays were used in our study. Experimental data revealed that inhibition of GSK3β could increase HIF1α protein levels and expression of its target genes by increasing the stability of the HIF1α mRNA, not by affecting the HIF1α protein stability, and that this process could be mediated by nucleolin.

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

Introduction. Aberrations of the Akt/mTOR/pS6 pathway have been linked to various types of human cancer, including oral squamous cell carcinoma (OSCC). The purpose of this study was to evaluate the activation status of Akt, mTOR, and pS6 in oral lichen planus (OLP) in comparison with oral premalignant and malignant lesions and normal oral mucosa (NM). Materials and Methods. Immunohistochemistry for p-Akt, p-mTOR, and phospho-pS6 was performed in 40 OLP, 20 oral leukoplakias (OL), 10 OSCC, and 10 control samples of NM. Results. Nuclear p-Akt expression was detected in the vast majority of cases in all categories, being significantly higher in OL. Cytoplasmic p-Akt and p-mTOR staining was present only in a minority of OLP cases, being significantly lower compared to OL and OSCC. Phospho-pS6 showed cytoplasmic positivity in most OLP cases, which however was significantly lower compared to OL and OSCC. Conclusions. Overall, cytoplasmic p-Akt, p-mTOR, and phospho-pS6 levels appear to be significantly lower in OLP compared to OL and OSCC. However, the expression of these molecules in a subset of OLP cases suggests that activation of Akt/mTOR/pS6 may occur in the context of OLP, possibly contributing to the premalignant potential of individual cases.

Dissecting the EGFR-PI3K-AKT pathway in oral cancer highlights the role of the EGFR variant III and its clinical relevance

Background

Dysregulated epidermal growth factor receptor (EGFR)-phosphoinositide-3-kinase (PI3K)-AKT signaling is considered pivotal for oral cancer, and the pathway is a potential candidate for therapeutic targeting.

Results

A total of 108 archival samples which were from surgically resected oral cancer were examined. Immunohistochemical staining showed the protein expression of membranous wild-type EGFR and cytoplasmic phosphorylated AKT was detected in 63.9% and 86.9% of the specimens, respectively. In 49.1% of the samples, no phosphatase and tensin homolog (PTEN) expression was detected. With regard to the EGFR variant III (EGFRvIII), 75.0% of the samples showed positive expression for moderate to severe staining, 31.5% of which had high expression levels. Real-time polymerase chain reaction assays for gene copy number assessment of PIK3CA revealed that 24.8% of the samples had alterations, and of EGFR showed that 49.0% had amplification. Direct sequencing of PIK3CA gene showed 2.3% of the samples had a hotspot point mutation. Statistical assessment showed the expression of the EGFRvIII correlated with the T classification and TNM stage. The Kaplan-Meier analyses for patient survival showed that the individual status of phosphorylated AKT and EGFRvIII led to significant differences in survival outcome. The multivariate analysis indicated that phosphorylated AKT, EGFRvIII expression and disease stage were patient survival determinants.

Conclusions

Aberrations in the EGFR-PI3K-AKT pathway were frequently found in oral cancers. EGFRvIII and phosphorylated AKT were predictors for the patient survival and clinical outcome.

The importance of oncogenic transcription factors for oral cancer pathogenesis and treatment

Oral squamous cell carcinoma is a major cause of morbidity and mortality worldwide. Current experimental evidence shows that most important risk factors for oral cancer include tobacco use and excessive alcohol consumption and less well-defined risks include viral infection and a diet deficient in antioxidants. The positive correlation between various risk/etiologic factors of oral cancer and the activation of various transcription factors (TFs) has been reported in the literature. Although initially, TFs were considered to be very difficult targets for use in clinical treatment, recent technological advances have provided the ability to control these factors of cancer progression. This review focuses on the role of oncogenic transcription factors in oral cancer, their modes of activation through various biological pathways, the promises and pitfalls in viewing them as potent oncotargets, the way they can be controlled based on the current understanding, and the future research to be done in this area.

Association of betel nut with carcinogenesis: revisit with a clinical perspective

Betel nut (BN), betel quid (BQ) and products derived from them are widely used as a socially endorsed masticatory product. The addictive nature of BN/BQ has resulted in its widespread usage making it the fourth most abused substance by humans. Progressively, several additives, including chewing tobacco, got added to simple BN preparations. This addictive practice has been shown to have strong etiological correlation with human susceptibility to cancer, particularly oral and oropharyngeal cancers.The PUBMED database was searched to retrieve all relevant published studies in English on BN and BQ, and its association with oral and oropharyngeal cancers. Only complete studies directly dealing with BN/BQ induced carcinogenesis using statistically valid and acceptable sample size were analyzed. Additional relevant information available from other sources was also considered.This systematic review attempts to put in perspective the consequences of this widespread habit of BN/BQ mastication, practiced by approximately 10% of the world population, on oral cancer with a clinical perspective. BN/BQ mastication seems to be significantly associated with susceptibility to oral and oropharyngeal cancers. Addition of tobacco to BN has been found to only marginally increase the cancer risk. Despite the widespread usage of BN/BQ and its strong association with human susceptibility to cancer, no serious strategy seems to exist to control this habit. The review, therefore, also looks at various preventive efforts being made by governments and highlights the multifaceted intervention strategies required to mitigate and/or control the habit of BN/BQ mastication.

Programmed cell death 4 nuclear loss and miR-21 or activated Akt overexpression in esophageal squamous cell carcinogenesis

The programmed cell death 4 (PDCD4) tumor suppressor is down-regulated in several malignancies, and the (subcellular) expression of its protein product is modulated by both oncomiR miR-21 and protein kinase B (Akt). PDCD4 and activated Akt (phosphorylated Akt [pAkt]) expression were assessed immunohistochemically in 53 tissue samples obtained from 25 endoscopic esophageal mucosal resections performed for squamous intraepithelial neoplasia (IEN) or squamous intramucosal carcinoma (IM-SSC). In total, 33 IEN (low-grade = 15; high-grade = 15) and 20 IM-SSC specimens were considered; 50 additional tissue samples of histologically proven normal esophageal mucosa were considered as normal controls. To further validate the results achieved, miR-21 expression (as assessed by quantitative real-time polymerase chain reaction and in situ hybridization) was tested in another series of 15 normal esophageal tissue samples, 15 high-grade IEN, and 15 IM-SCCs. Normal suprabasal squamous epithelial layers consistently featured strong PDCD4 nuclear immunostaining, which was significantly lower (P < 0.001) in IEN (both low-and high-grade) and in IM-SSC. Conversely, pAkt and miR-21 expression was significantly up-regulated in the whole spectrum of preneoplastic/neoplastic lesions considered. PDCD4 down-regulation, as assessed by immunohistochemistry, is a reliable biomarker of early-stage squamous cell esophageal neoplasia, providing additional information in the histological assessment of these lesions.

TWIST and p-Akt immunoexpression in normal oral epithelium, oral dysplasia and in oral squamous cell carcinoma

Objectives: The aim of this study was to evaluate the immunoexpression of TWIST and p-Akt proteins in oral leukoplakia (OL) and oral squamous cell carcinoma (OSCC), correlating their expressions with the histological features of the lesions. Study design: Immunohistochemical studies were carried out on 10 normal oral epithelium, 30 OL and 20 OSCC formalin-fixed, paraffin-embedded tissue samples. Immunoperoxidase reactions for TWIST and p-Akt proteins were applied on the specimens and the positivity of the reactions was calculated for 1000 epithelial cells. Results: Kruskal-Wallis and Dunn’s post tests revealed a significant difference in TWIST and p-Akt immunoexpression among normal oral mucosa, OL and OSCC. In addition, a significant positive correlation was found between TWIST and p-Akt expressions according to the Pearson’s correlation test. Conclusions: The results obtained in the current study suggest that TWIST and p-Akt may participate of the multi-step process of oral carcinogenesis since its early stages.

Key words: Oral cancer, oral leukoplakia, dysplasia, immunohistochemistry.

Glycogen synthase kinase 3 beta: can it be a target for oral cancer

Despite progress in treatment approaches for oral cancer, there has been only modest improvement in patient outcomes in the past three decades. The frequent treatment failure is due to the failure to control tumor recurrence and metastasis. These failures suggest that new targets should be identified to reverse oral epithelial dysplastic lesions. Recent developments suggest an active role of glycogen synthase kinase 3 beta (GSK3 β) in various human cancers either as a tumor suppressor or as a tumor promoter. GSK3β is a Ser/Thr protein kinase, and there is emerging evidence that it is a tumor suppressor in oral cancer. The evidence suggests a link between key players in oral cancer that control transcription, accelerated cell cycle progression, activation of invasion/metastasis and anti-apoptosis, and regulation of these factors by GSK3β. Moreover, the major upstream kinases of GSK3β and their oncogenic activation by several etiological agents of oral cancer support this hypothesis. In spite of all this evidence, a detailed analysis of the role of GSK3β in oral cancer and of its therapeutic potential has yet to be conducted by the scientific community. The focus of this review is to discuss the multitude of roles of GSK3β, its possible role in controlling different oncogenic events and how it can be targeted in oral cancer.