Squamous cell carcinoma of the oral cavity and circulating tumour cells

Circulating Tumor Cells in Oral Cancer

Till now, oral squamous cell carcinoma (OSCC) is graded as well-differentiated, moderately-differentiated, poorly-differentiated, and undifferentiated. However, this grading does not have a prediction of the prognosis of the patient. Also, prognosis impacts lymph node metastases, surgical margins, and vascular invasions (neural invasion, muscular invasion, salivary gland invasion). The prognosis of lymph node metastases is significant, which affects the survival of the patients which is 50%. So, a dependable blood marker is needed for prognosis in OSCC patients with loco-regional and distant recurrence. Some factors can be assisted only after surgery and invasive techniques to check the prognosis of the disease. Despite the ease of examining the oral cavity, there is no practical approach for non-invasive screening and detecting cancer. As it is abrupt to use such invasive procedures from time to time, there is a need for nonsurgical and reliable techniques to assess the progression of tumors. Also, frozen sections are helpful during the intraoperative procedure to evaluate the lymph node metastases. An increase in the number of tumor cells through blood is a significant event in disease metastases toward the peripheral blood. Oral health impact assessment instruments could aid in determining the quality of life, and their usage in the initial stages of oral carcinoma could help physicians choose the best treatment option for enhancing the quality of life.

Label-Free Optical Spectroscopy for Early Detection of Oral Cancer

Oral cancer is the 16th most common cancer worldwide. It commonly arises from painless white or red plaques within the oral cavity. Clinical outcome is highly related to the stage when diagnosed. However, early diagnosis is complex owing to the impracticality of biopsying every potentially premalignant intraoral lesion. Therefore, there is a need to develop a non-invasive cost-effective diagnostic technique to differentiate non-malignant and early-stage malignant lesions. Optical spectroscopy may provide an appropriate solution to facilitate early detection of these lesions. It has many advantages over traditional approaches including cost, speed, objectivity, sensitivity, painlessness, and ease-of use in clinical setting for real-time diagnosis. This review consists of a comprehensive overview of optical spectroscopy for oral cancer diagnosis, epidemiology, and recent improvements in this field for diagnostic purposes. It summarizes major developments in label-free optical spectroscopy, including Raman, fluorescence, and diffuse reflectance spectroscopy during recent years. Among the wide range of optical techniques available, we chose these three for this review because they have the ability to provide biochemical information and show great potential for real-time deep-tissue point-based in vivo analysis. This review also highlights the importance of saliva-based potential biomarkers for non-invasive early-stage diagnosis. It concludes with the discussion on the scope of development and future demands from a clinical point of view.

Circulating biomarkers in oral cancer: Unravelling the mystery

Oral squamous cell carcinoma (OSCC) is among the most common malignancies and a leading cause of death in developing countries. Late diagnosis and regional and/or distant metastasis worsen the prognosis of this condition. Despite the advances in diagnostic modalities and management strategies, there is little improvement in the 5-year survival rate. A deeper insight into the molecular events of various tumours has enabled the use of minimally invasive methods for monitoring disease progression, prognostication and treatment monitoring. Although studies in OSCC are preliminary, the use of liquid biopsies has opened new frontiers for the development of biomarkers that can serve as alternatives to conventional biopsies and imaging methods. Circulating biomarkers in blood allow for the real-time monitoring of tumour and therapeutic responses. This review aims to outline the promises and challenges of circulating biomarkers in OSCC with special emphasis on circulating tumour cells, circulating tumor DNA, and exosomes.

CRISPR/Cas gene-editing technology and its advances in dentistry

A recent discovery of revolutionary Clustered regularly interspaced palindromic repeats (CRISPR) is a gene-editing tool that provides a type of adaptive immunity in prokaryotic organisms, which is currently used as a revolutionizing tool in biomedical research. It has a mechanism of correcting genome errors, turning on/off genes in cells and organisms. Most importantly playing a crucial function in bacterial defence by identifying and destroying Deoxyribonucleic acid (DNA) segments during bacteriophage invasions since the CRISPR-associated protein 9 (Cas9) enzyme recognizes and cleaves invasive DNA sequences complementary to CRISPR. Therefore, researchers employ this biological device to manipulate the genes to develop new therapies to combat systemic diseases. Currently, the most significant advance at the laboratory level is the generation of cell and animal models, functional genomic screens, live images of the cell genome, and defective DNA repairs to find the cure for genetic disorders. Even though this technology has enormous biomedical applications in various sectors, this review will summarize CRISPR/Cas emphasizing both the therapeutic and diagnostic mechanisms developed in the field of dentistry and the promising attempts to transfer this technology to clinical application. Finally, future developments are also described, which proposes to use CRISPR/Cas systems for prospective clinical dentistry applications.

Expression of Ubiquitin-specific protease 7 in oral squamous cell carcinoma promotes tumor cell proliferation and invasion

Oral Squamous Cell Carcinoma (OSCC) is the most common malignant cancer affecting oral cavity. Recent studies have demonstrated that Ubiquitin-specific protease 7 (USP7) was upregulated in several types of cancers. USP7 expression was associated with various proto-oncogenes and tumor suppressor genes. However, USP7 expression level and its functional role in OSCC is unclear. In the current study, we showed that USP7 expression in OSCC tissues was generally upregulated compared to normal adjacent tissues by using IHC. Furthermore, statistical analysis uncovered that USP7 expression was positively correlated with Ki-67, MMP2, VEGF in OSCC tissues. Importantly, high USP7 expression was significantly correlated with lymph node metastasis and histological differentiation in OSCC patients. So, our hypothesis is that USP7 plays a tumor-promoting role in OSCC. Knocking down of USP7 in tumor cells not only suppressed HSC3 cells proliferation, migration and invasion, but also promoted cell apoptosis. Moreover, USP7 siRNA blocked the activation of Akt/ERK signaling pathway. In conclusion, data presented here suggests that USP7 promotes the progression of OSCC. USP7 may be used as a new therapeutic target for OSCC diagnosis and treatment.

FERMT1 knockdown inhibits oral squamous cell carcinoma cell epithelial-mesenchymal transition by inactivating the PI3K/AKT signaling pathway

BACKGROUND

The metastasis of oral cancer is one of the main causes of death. However, the mechanisms underlying oral cancer metastasis have not been completely elucidated. Fermitin family member 1 (FERMT1) plays an -oncogene role in many cancers; however, the role of FERMT1 in oral squamous cell cancer (OSCC) remains unclear.

METHODS

In this study, OSCC cells were treated with 5 ng/ml recombinant human Transforming growth factor-β1 (TGF-β1) protein. FERMT1 expression was measured in OSCC cell lines by RT-qPCR and western blotting. The effect of FERMT1 knockdown on the migration and invasion of OSCC cells was evaluated by Transwell assay. The epithelial-mesenchymal transition (EMT) and PI3K/AKT signaling pathway-related mRNA expression and protein levels were assessed by RT-qPCR and western blotting.

RESULTS

We found that FERMT1 expression was elevated in TGF-β1-induced OSCC cell lines, and knockdown of FERMT1 inhibited the migration and invasion in TGF-β1-induced OSCC cells. FERMT1 silencing inhibited vimentin, N-cadherin, matrix metalloproteinase 9 (MMP-9) expression and promoted E-cadherin expression, suggesting that FERMT1 silencing inhibited EMT in TGF-β1-induced OSCC cells. Furthermore, FERMT1 silencing inactivated the PI3K/AKT signaling pathway in TGF-β1-induced OSCC cells. Activation of the PI3K/AKT signaling pathway reversed the effect of FERMT1 silencing on OSCC cell migration, invasion, and EMT.

CONCLUSIONS

FERMT1 silencing inhibits the migration, invasion, and EMT of OSCC cells via inactivation of the PI3K/AKT signaling pathway, suggesting that FERMT1 is a novel and potential therapeutic target for anti-metastatic strategies for OSCC.

MMP-9 Knockdown Inhibits Oral Squamous Cell Carcinoma Lymph Node Metastasis in the Nude Mouse Tongue-Xenografted Model through the RhoC/Src Pathway

Oral squamous cell carcinoma (OSCC) is one of the most common types of cancers in developing countries. A major contributor to the high mortality rate of OSCC is the tendency of oral cancer cells to metastasize to lymph nodes around the head and neck during the early stages of cancer development. Matrix metalloproteinase 9 (MMP-9), an endopeptidase, can degrade the extracellular matrix and basement membrane and plays a key role in tumor invasion and metastasis. In vitro, cell migration ability was conducted by scratching assays. We also investigated the interaction abilities between OSCC cells and vascular endothelial cells (ECs) by an adhesion assay and transendothelial migration assay. And we established a BALB/c nude mouse tongue-xenografted metastasis model to investigate the role of MMP-9 and explore its potential underlying mechanism in OSCC growth, lymph node metastasis, and angiogenesis in vivo. The results showed that knockdown of MMP-9 could significantly suppress OSCC cell migration, proliferation, interactions between endothelial cells, xenografted tumor growth, and angiogenesis and simultaneously markedly inhibited OSCC cell metastasis to mouse lymphonodi cervicales superficiales, axillary lymph nodes, and even distant inguinal lymph nodes. Mechanistic studies revealed that knockdown of MMP-9 also led to a decreased expression of RhoC, Src, and F-actin by RT-PCR, western blotting, and immunohistochemistry. And the bioinformatic analysis showed that MMP-9, RhoC, and Src mRNA expression was positively and linearly correlated in OSCC on TCGA database. Together, our findings indicated that MMP-9 plays a very important role in OSCC growth, migration, angiogenesis, and lymph node metastasis, and its potential mechanism may be mediated by RhoC and Src gene expression.

MiR-590-5p regulates cell proliferation, apoptosis, migration and invasion in oral squamous cell carcinoma by targeting RECK

OBJECTIVE

To discover the role of miR-590-5p in oral squamous cell carcinoma (OSCC) progression and the corresponding mechanism via the targeting RECK.

METHODS

OSCC (n=85) and normal oral tissues (n=60) were collected to quantify the miR-590-5p expression by using qRT-PCR. Then SCC-15 and OEC-M1 cells were selected and divided into Mock, inhibitor NC, miR-590-5p inhibitor, si-RECK and miR-590-5p inhibitor + si-RECK groups. Dual-luciferase reporter gene assay was used to verify if miR-590-5p could target RECK. The biological behaviors of OSCC cells were evaluated by MTT, Wound-healing, Transwell and Flow cytometry. The expression of miR-590-5p and RECK was measured by qRT-PCR and Western blotting , respectively.

RESULTS

Overexpression of miR-590-5p was found in OSCC tissues. The expression of miR-590-5p was significantly associated with the clinical TNM stage, differentiation degree, and lymph node metastasis of OSCC. RECK was identified as a direct target of miR-590-5p. Compared with the Mock group, cells in the miR-590-5p inhibitor group were decreased in terms of proliferation, invasion, and migration, and increased in cell apoptosis, accompanied by down-regulated miR-590-5p, Bcl-2/Bax and MMP-9, and up-regulated RECK. By contrast, si-RECK group presented completely opposite changes, and si-RECK reversed the inhibitory effect of miR-590-5p inhibitor on the OSCC cell growth.

CONCLUSION

MiR-590-5p expression was obviously increased in OSCC, and inhibiting miR-590-5p enhanced the expression of its target gene RECK, thereby suppressing proliferation, migration and invasion of OSCC cells and promoting apoptosis of OSCC cells.

MicroRNA-345 functions as a tumor suppressor via targeting ZEB2 in oral squamous cell carcinoma

OBJECTIVE

The objective of this study was to explore the role of miRNAs in OSCC and to identify potential novel biomarkers or therapeutic agents in OSCC treatment.

DESIGN

Microarray analysis and quantitative reverse transcription polymerase chain reaction (qRT-PCR) were performed to identify and verify differentially expressed miRNAs in OSCC tissues. The migration, invasion, proliferation and cell cycle of OSCC cells were analyzed to determine the function of miR-345 in OSCC development. Bioinformatics analysis and Dual-luciferase reporter assays were performed to identify and verify the target of miR-345.

RESULTS

The results showed a total of 17 miRNAs with significantly different expression in OSCC tissues (5 upregulated miRNAs and 12 downregulated miRNAs), including miR-345. The microarray results were also validated by qRT-PCR using 22 pairs of cancerous tissues and matched non-cancerous healthy samples. In particular, miR-345 expression was significantly lower in OSCC tissues. In addition, overexpression of miR-345 mimics in OSCC cells significantly inhibited their migration, invasion and proliferation while inducing cell cycle arrest in the G1 phase. Bioinformatics analysis predicted ZEB2 (zinc finger E-box-binding homeobox 2) as a potential target of miR-345, and luciferase reporter assays confirmed that miR-345 targeted ZEB2 through direct binding the 3' untranslated region of ZEB2. Furthermore, miR-345 overexpression in OSCC reduced both mRNA and protein expression of ZEB2.

CONCLUSIONS

The results of this study indicated that miR-345 functions as a tumor suppressor to target ZEB2 in OSCC. These findings suggest that the miR-345/ZEB2 axis may be used as a potential therapeutic target in OSCC treatment.

Nanomedical detection and downstream analysis of circulating tumor cells in head and neck patients

The establishment of novel biomarkers in liquid biopsies of cancer patients has come more into focus in prognostic and diagnostic research efforts. Due to their prognostic relevance disseminated tumor cells or circulating tumor cells are the subject of intensive research and are discussed as early diagnostic indicators for treatment failure and the formation of micrometastases. A potential association of this early-systemic tumor component with poor prognosis of cancer patients could be already demonstrated for various entities including breast, colon, lung, melanoma, ovarian and prostate cancers. Thus, the detection of circulating tumor cells seems to be also applicable for minimal-invasive monitoring of therapy progress in head and neck cancer patients. A major problem of the use in clinical routine is that circulating tumor cells could not be detected by modern imaging techniques. To overcome these limitations highly sensitive detection methods and techniques for their molecular characterization are urgently needed allowing mechanistic understanding and targeting of circulating tumor cells. Especially the medical application of nanotechnology (nanomedical methods) has made valuable contributions to the field. Here, we want to provide a comprehensive overview on (nanomedical) detection methods for circulating tumor cells and discuss their merits, pitfalls and future perspectives especially for head and neck solid squamous cell carcinoma (HNSCC) patients.

Ganoderma lucidum Polysaccharide (GLP) Inhibited the Progression of Oral Squamous Cell Carcinoma via the miR-188/BCL9/β-Catenin Pathway

Objective. The effects of Ganoderma lucidum polysaccharide (GLP) on the proliferation and migration of oral squamous cell carcinoma (OSCC) cells (HSC-3) were investigated in this study. Methods. Oral squamous cell carcinoma (OSCC) cells (HSC-3) were cultured in vitro and were treated with different concentrations of GLP. CCK-8 assay and scratch assay were then used to detect the inhibitory effect of GLP on these cells. qRT-PCR and western blot were used to measure the expression changes of the genes involved in the miR-188 and β-catenin signaling pathways. Results. GLP had significant cytotoxicity to HSC-3 cells and was capable of inhibiting the proliferation and migration of HSC-3 cells. GLP upregulated the expression of miR-188 in HSC-3 cells and via which inhibited the proliferation and migration of HSC-3 cells. In addition, miR-188 inhibited the activation of the β-catenin signaling pathway through its target BCL9. Conclusions. GLP inhibited the proliferation and migration of OSCC cells (HSC-3) by regulating the miR-188/BCL9/β-catenin signaling pathway. The results in this study provided a theoretical basis for the treatment of OSCC with GLP.

Selectin Binding Sites Are Involved in Cell Adhesive Properties of Head and Neck Squamous Cell Carcinoma

The formation of distant metastases often determines the fate of patients with head and neck squamous cell carcinoma (HNSCC). The expression of cell adhesion molecules (CAMs) and their ligands of the leukocyte adhesion cascade has been associated with metastatic competence in several malignant entities. In this study, human HNSCC cell lines were analyzed in vitro and in a spontaneous metastatic xenograft model. Immunohistochemical analyses of several CAMs were performed on xenograft tumors and tissue microarrays (TMA) from 453 patients with head and neck squamous cell carcinomas with full histo-pathological and clinical follow-up data. UTSCC 24A and 24B cells bind to E-selectin in vitro, show E-selectin dependent binding to human umbilical vein endothelial cells (HUVECs), and express sLeX. All HNSCC cells engrafted into severe combined immunodeficient (SCID) mice, and UTSCC 24A cells formed sporadically spontaneous lung metastases. The expression of CAMs varied between the cell lines, but a correlation between tumor growth and metastatic potential did not exist. None of the CAMS or their ligands could be identified to be of prognostic relevance in the TMA study. The in vitro results indicate that E-selectin and sLeX are involved in the adhesion of HNSCC cells to endothelium. However, specific prognostic markers chosen from the leukocyte adhesion cascade for HNSCC were not identified.

Squamous Cell Carcinoma of Left Buccal Alveolar Ridge

Squamous cell carcinoma (SCC) of the oral cavity accounts for 4% of malignancies in men and 2% of malignancies in women, and is responsible for 3% of all cancer deaths. Cancers of the gingiva often escape early detection and lead to a delay in intervention, since their signs and symptoms resemble common dental and periodontal infections. Here we present a case of a 55-year-old female patient who presented to our clinic with a left lower gingival mass for two weeks. Based on the clinical presentation, and possible differential diagnosis, this case highlights the importance of timely intervention and management. 

Construction of prognostic risk prediction model of oral squamous cell carcinoma based on co-methylated genes

This study aimed to identify DNA methylation markers in oral squamous cell carcinoma (OSCC) and to construct a prognostic prediction model of OSCC. For this purpose, the methylation data of patients with OSCC downloaded from The Cancer Genome Atlas were considered as a training dataset. The methylation profiles of GSE37745 for OSCC samples were downloaded from Gene Expression Omnibus and considered as validation dataset. Differentially methylated genes (DMGs) were screened from the TCGA training dataset, followed by co-methylation analysis using weighted correlation network analysis (WGCNA). Subsequently, the methylation and gene expression levels of DMGs involved in key modules were extracted for correlation analysis. Prognosis-related methylated genes were screened using the univariate Cox regression analysis. Finally, the risk prediction model was constructed and validated through GSE52793. The results revealed that a total of 948 DMGs with CpGs were screened out. Co-methylation gene analysis obtained 2 (brown and turquoise) modules involving 380 DMGs. Correlation analysis revealed that the methylation levels of 132 genes negatively correlated with the gene expression levels. By combining with the clinical survival prognosis of samples, 5 optimized prognostic genes [centromere protein V (CENPV), Tubby bipartite transcription factor (TUB), synaptotagmin like 2 (SYTL2), occludin (OCLN) and CAS1 domain containing 1 (CASD1)] were selected for constructing a risk prediction model. It was consistent in the training dataset and GSE52793 that low-risk samples had a better survival prognosis. On the whole, this study indicates that the constructed risk prediction model based on CENPV, SYTL2, OCLN, CASD1, and TUB may have the potential to be used for predicting the survival prognosis of patients with OSCC.

Pristimerin induces apoptosis of oral squamous cell carcinoma cells via G1 phase arrest and MAPK/Erk1/2 and Akt signaling inhibition

Pristimerin is an active compound isolated from the traditional Chinese herbs Celastraceae and Hippocrateaceae. It has been reported to exert antitumor effects under experimental and clinical conditions; however, the antitumor effects and underlying mechanisms of pristimerin in oral cancer cells have not yet been identified. In the present study, the anticancer potential of pristimerin was investigated in two oral squamous cell carcinoma (OSCC) cell lines, CAL-27 and SCC-25. Results demonstrated that pristimerin was toxic against the two cell lines, and exhibited inhibitory effects against proliferation. Furthermore, pristimerin exhibited a more potent anti-proliferative activity in CAL-27 and SCC-25 cells than the common chemotherapy drugs cisplatin and 5-fluorouracil. In addition, cell cycle distribution analysis revealed that G₀/G₁ phase arrest was induced following pristimerin treatment in CAL-27 and SCC-25 cells, which was strongly associated with upregulation of p21 and p27, coupled with downregulation of cyclin D1 and cyclin E. Meanwhile, pristimerin induced significant apoptosis of CAL-27 and SCC-25 cells, alongside decreased levels of caspase-3 and specific cleavage of poly (ADP-ribose) polymerase. These effects were associated with inhibition of the mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2 and protein kinase B signaling pathways. With regards to these results, pristimerin may be considered a potent novel active substance for the treatment of OSCC.

Expression of USP22 and the chromosomal passenger complex is an indicator of malignant progression in oral squamous cell carcinoma

Oral cancer is a common cancer of the head and neck. Oral squamous cell carcinoma (OSCC) represents almost 90% of the total cases of head and neck cancer. Ubiquitin-specific protease 22 (USP22) is a deubiquitinating hydrolase, and it is highly expressed in various types of cancer, which also typically have a poor prognosis. Aurora-B and Survivin, which belong to the chromosomal passenger complex, are also highly expressed in a number of types of cancer. In the present study, USP22 expression and its associations with Aurora-B and Survivin, and the clinicopathological features in OSCC were explored. USP22 is highly expressed in OSCC. Overexpression of USP22 is associated with lymph node metastasis and histological grade (P<0.01). Additionally, the expression of USP22 was positively associated with Aurora-B (P<0.01), Survivin (P<0.01), and Ki-67 (P<0.01). Furthermore, USP22 small interfering RNA inhibited cell growth and reduced the expression levels of Aurora-B, Survivin and Cyclin B, together with the upregulation of cyclin-dependent kinase inhibitor 1A (p21). These data suggest that USP22, Aurora-B and Survivin promote the OSCC development and may represent novel targets for OSCC diagnosis and treatment in the future.

Flubendazole and mebendazole impair migration and epithelial to mesenchymal transition in oral cell lines

Benzimidazole anthelmintics flubendazole and mebendazole are microtubule-targeting drugs that showed considerable anti-cancer activity in different preclinical models. In this study, the effects of flubendazole and mebendazole on proliferation, migration and cadherin switching were studied in a panel of oral cell lines in vitro. Both compounds reduced the viability of the PE/CA-PJ15 and H376 oral squamous carcinoma cells and of the premalignant oral keratinocytes DOK with the IC₅₀ values in the range of 0.19-0.26 μM. Normal oral keratinocytes and normal gingival fibroblasts were less sensitive to the treatment. Flubendazole and mebendazole also reduced the migration of the PE/CA-PJ15 cell in concentrations that had no anti-migratory effects on the normal gingival fibroblasts. Levels of the focal adhesion kinase FAK, Rho-A and Rac1 GTPases and the Rho guanine nucleotide exchange factor GEF-H1 were decreased in both PE/CA-PJ15 cells and gingival fibroblasts following treatment. Both drugs also interfered with cadherin switching in the model of TGF-β-induced epithelial to mesenchymal transition (EMT) in the DOK cell line. Levels of N-cadherin were reduced in the TGF-β induced cells co-treated with flubendazol and mebendazole in very low concentration (50 nM). These results suggest direct effects of both benzimidazoles on selected processes of EMT in oral cell lines such as cadherin switching as well as cellular migration.

Early discovery of disseminated tumor cells during carcinogenesis in a 4NQO-induced mouse model of oral squamous cell carcinoma

OBJECTIVES

Heterogeneous cells appear in multiple organs during the same time period as the primary lesion of some tumors is clinically detected. These heterogeneous cells are also known as disseminated tumor cells (DTCs). However, the characteristics of DTCs that disseminate during oral carcinogenesis remain unclear.

MATERIALS AND METHODS

A mouse 4NQO model of lymph node metastasis in oral squamous cell carcinoma was established. Tissue samples of the tongue, bone marrow and submandibular lymph node were collected. Five stages (stage 0~stage IV) of carcinogenesis in each experimental animal were classified by two pathologists. After immunohistochemical staining of cytokeratin, the DTCs were isolated from bone marrow samples (stage II) by the laser capture microdissection (LCM) technique during oral carcinogenesis. Genomic amplification of bone marrow DTCs was performed, and homozygous deletion of the RB1CC1 gene was analyzed. After confirming the presence of disseminated tumor cells in stage II bone marrow samples, a comprehensive study among various stages of lymph node tissue was conducted using the same method.

RESULTS

DTCs that spread from the primary tumor were discovered in stage II bone marrow samples and in stage I, stage II and stage III submandibular lymph node samples through immunohistochemical staining. These spreading cells had different levels of homozygous exon deletion in the RB1CC1 and TP53 genes.

CONCLUSION

Early spreading of epithelial cells may occur during the carcinogenesis of oral cancer. DTCs of oral carcinoma may show different chromosome aberrations from matched primary tumor cells.

Nanotechnology: a promising method for oral cancer detection and diagnosis

Oral cancer is a common and aggressive cancer with high morbidity, mortality, and recurrence rate globally. Early detection is of utmost importance for cancer prevention and disease management. Currently, tissue biopsy remains the gold standard for oral cancer diagnosis, but it is invasive, which may cause patient discomfort. The application of traditional noninvasive methods-such as vital staining, exfoliative cytology, and molecular imaging-is limited by insufficient sensitivity and specificity. Thus, there is an urgent need for exploring noninvasive, highly sensitive, and specific diagnostic techniques. Nano detection systems are known as new emerging noninvasive strategies that bring the detection sensitivity of biomarkers to nano-scale. Moreover, compared to current imaging contrast agents, nanoparticles are more biocompatible, easier to synthesize, and able to target specific surface molecules. Nanoparticles generate localized surface plasmon resonances at near-infrared wavelengths, providing higher image contrast and resolution. Therefore, using nano-based techniques can help clinicians to detect and better monitor diseases during different phases of oral malignancy. Here, we review the progress of nanotechnology-based methods in oral cancer detection and diagnosis.

MicroRNA-205-5p suppresses the invasiveness of oral squamous cell carcinoma by inhibiting TIMP‑2 expression

MicroRNAs (miRNAs or miRs) play important roles in carcinogenesis. The miRNA, miR-205-5p, has been reported to suppress the growth of various types of tumor; however, its functional contribution to oral squamous cell carcinoma (OSCC) is not yet clear. Thus, this study was conducted to determine the miRNA expression signatures in OSCC and to investigate the functional role of miR‑205‑5p in OSCC cells. We measured miR‑205‑5p expression by RT-qPCR, and examined the function of miR‑205‑5p by transfecting a miR‑205‑5p mimic or inhibitor into OSCC cells and measuring cell proliferation, migration and invasiveness. Genes targeted by miR‑205‑5p were identified using the TargetScan database and verified by western blot analysis, luciferase reporter assay and ELISA. We found that miR‑205‑5p was significantly downregulated in OSCC cell lines and tissue specimens. Following transfection of miR‑205‑5p mimic or inhibitor into the cancer cell lines, miR‑205‑5p overexpression significantly suppressed cancer cell migration and invasion. We further demonstrated that miR‑205‑5p directly targeted and regulated the tissue inhibitor of metalloproteinases‑2 (TIMP‑2) gene. The silencing of TIMP‑2 suppressed cancer cell invasion and the activation of pro‑matrix metalloproteinase‑2 (pro‑MMP‑2). These results suggest that TIMP‑2 promotes tumor progression, and that miR‑205‑5p directly regulates TIMP‑2, thereby suppressing pro‑MMP‑2 activation and inhibiting OSCC cell invasiveness. Our data describing the pathways regulated by miR‑205‑5p provide new insight into the mechanisms responsible for OSCC development and metastasis.

Regulation of ITGA3 by the anti-tumor miR-199 family inhibits cancer cell migration and invasion in head and neck cancer

For patients with head and neck squamous cell carcinoma (HNSCC), survival rates have not improved due to local recurrence and distant metastasis. Current targeted molecular therapies do not substantially benefit HNSCC patients. Therefore, it is necessary to use advanced genomic approaches to elucidate the molecular mechanisms underlying the aggressiveness of HNSCC cells. Analysis of our microRNA (miRNA) expression signature by RNA sequencing showed that the miR‐199 family (miR‐199a‐5p, miR‐199a‐3p, miR‐199b‐5p and miR‐199b‐3p) was significantly reduced in cancer tissues. Ectopic expression of mature miRNA demonstrated that all members of the miR‐199 family inhibited cancer cell migration and invasion by HNSCC cell lines (SAS and HSC3). These findings suggested that both passenger strands and guide strands of miRNA are involved in cancer pathogenesis. In silico database and genome‐wide gene expression analyses revealed that the gene coding for integrin α3 (ITGA3) was regulated by all members of the miR‐199 family in HNSCC cells. Knockdown of ITGA3 significantly inhibited cancer cell migration and invasion by HNSCC cells. Moreover, overexpression of ITGA3 was confirmed in HNSCC specimens, and high expression of ITGA3 predicted poorer survival of the patients (P = 0.0048). Our data revealed that both strands of pre‐miR‐199a (miR‐199a‐5p and miR‐199a‐3p) and pre‐miR‐199b (miR‐199b‐5p and miR‐199b‐3p) acted as anti‐tumor miRNA in HNSCC cells. Importantly, the involvement of passenger strand miRNA in the regulation of cellular processes is a novel concept in RNA research. Novel miRNA‐based approaches for HNSCC can be used to identify potential targets for the development of new therapeutic strategies.

MicroRNA‑375 inhibits oral squamous cell carcinoma cell migration and invasion by targeting platelet‑derived growth factor‑A

MicroRNA‑375 (miR‑375) serves an important role in cancer development and growth. However, little is known about the role of miR‑375 in the regulation of oral squamous cell carcinoma (OSCC) metastasis and invasion. The present study measured the expression levels of miR‑375 in Tca8113, UM2, UM1 and CAL‑27 cell lines, using reverse transcription‑quantitative polymerase chain reaction. The results demonstrated that miR‑375 expression levels were significantly reduced in UM1 and CAL‑27 (highly metastatic) compared with Tca8113 and UM2 (less aggressive) OSCC cell lines. Furthermore, it was revealed that overexpression of miR‑375 suppressed the migration and invasion of UM1 cells. Based on a luciferase reporter assay, platelet‑derived growth factor‑A (PDGF‑A) was identified as a direct target gene of miR‑375. Additionally, overexpression of PDGF‑A significantly reversed the effect of miR‑375 on cell migration and invasion in UM1 cells. These data demonstrated that miR‑375 suppressed OSCC cell migration and invasion by targeting PDGF‑A, which may be a potential therapeutic target for the treatment of OSCC.

Circulating tumor stem like cells in oral squamous cell carcinoma: An unresolved paradox

OBJECTIVE

Circulating tumor cells (CTCs) are increasingly gaining importance due to their immense potential in enhancing diagnosis, prognosis and response to therapy in solid malignancies. Therefore, we aimed to comprehend the molecular diversity and critical role of this disseminated tumor population in OSCC.

METHODOLOGY

CD44+ subpopulation was isolated using immuno-magnetic cell separation and their purity was validated using flow cytometry. Characterisation of self renewal potential and resistance to chemotherapy was assessed using tumor sphere forming and cytotoxicity assay. Gene expression profile of pertinent CSC (CD44s, CD44v3, CD44v6) and stemness markers (Bmi1 and Nanog) was carried out in CD44+ cells using Real Time PCR. Predominantly expressed markers and their association with clinico-pathological conditions were substantiated in 30 OSCC patients.

RESULT

Flow cytometry analysis depicted a predominant population of CD44+CD24-CD45- cells suggesting that circulating tumor cells had a subpopulation of CSC like cells in the circulation. These cells demonstrated increased sphere forming capability and intrinsic chemo-resistance compared to non-CSC, thus indicating the CSC features of self-renewal and chemo-resistance. Additionally, CD44+ cells showed significantly increased expression levels of CD44v6 and Nanog compared to CD44- cells. Clinically, expression pattern of CD44v6 and Nanog correlated with different anatomical subsites, loco-regional aggressiveness of the disease and recurrence, thus opening newer avenues that can be explored for better prognostic and therapeutic implications.

CONCLUSION

This study explored the inevitable role of CD44v6 and Nanog as circulating stem like cell markers in assessment of loco-regional aggressiveness, detection of relapse and therapeutic response and resistance.

Osteoactivin Promotes Migration of Oral Squamous Cell Carcinomas

Nearly 50% of patients with oral squamous cell carcinoma (OSCC) die of metastases or locoregional recurrence. Metastasis is mediated by cancer cell adhesion, migration, and invasion. Osteoactivin (OA) overexpression plays a role in metastases in several malignancies. The aims were to determine how integrin interactions modulate OA-induced OSCC cell migration; and to investigate OA effects on cell survival and proliferation. We confirmed OA mRNA and protein overexpression in OSCC cell lines. We assessed OA's interactions with integrins using adhesion inhibition assays, fluorescent immunocytochemistry and co-immunoprecipitation. We investigated OA-mediated activation of mitogen-activated protein kinases (MAPKs) and cell survival. Integrin inhibition effects on OA-mediated cell migration were determined. We assessed effects of OA knock-down on cell migration and proliferation. OA is overexpressed in OSCC cell lines, and serves as a migration-promoting adhesion molecule. OA co-localized with integrin subunits, and co-immunoprecipitated with the subunits. Integrin blocking antibodies, especially those directed against the β1 subunit, inhibited cell adhesion (P = 0.03 for SCC15 cells). Adhesion to OA activated MAPKs in UMSCC14a cells and OA treatment promoted survival of SCC15 cells. Integrin-neutralizing antibodies enhanced cell migration with OA in the extracellular matrix. OA knock-down resulted in decreased proliferation of SCC15 and SCC25 cells, but did not inhibit cell migration. OA in the extracellular matrix promotes OSCC cell adhesion and migration, and may be a novel target in the prevention of HNSCC spread. J. Cell. Physiol. 231: 1761-1770, 2016. © 2015 Wiley Periodicals, Inc.

Porphyromonas gingivalis initiates a mesenchymal-like transition through ZEB1 in gingival epithelial cells

The oral anaerobe Porphyromonas gingivalis is associated with the development of cancers including oral squamous cell carcinoma (OSCC). Here, we show that infection of gingival epithelial cells with P. gingivalis induces expression and nuclear localization of the ZEB1 transcription factor, which controls epithelial-mesenchymal transition. P. gingivalis also caused an increase in ZEB1 expression as a dual species community with Fusobacterium nucleatum or Streptococcus gordonii. Increased ZEB1 expression was associated with elevated ZEB1 promoter activity and did not require suppression of the miR-200 family of microRNAs. P. gingivalis strains lacking the FimA fimbrial protein were attenuated in their ability to induce ZEB1 expression. ZEB1 levels correlated with an increase in expression of mesenchymal markers, including vimentin and MMP-9, and with enhanced migration of epithelial cells into matrigel. Knockdown of ZEB1 with siRNA prevented the P. gingivalis-induced increase in mesenchymal markers and epithelial cell migration. Oral infection of mice by P. gingivalis increased ZEB1 levels in gingival tissues, and intracellular P. gingivalis were detected by antibody staining in biopsy samples from OSCC. These findings indicate that FimA-driven ZEB1 expression could provide a mechanistic basis for a P. gingivalis contribution to OSCC.

Inhibition of autophagy by 3-MA enhances IL-24-induced apoptosis in human oral squamous cell carcinoma cells

Background

Interleukin-24(IL-24), also referred to as melanoma differentiation-associated gene-7(mda-7), is a unique member of the IL-10 gene family, which displays nearly ubiquitous cancer-specific toxicity. The most notable feature of IL-24 is selectively induced growth suppression and apoptosis in various cancer cells, with no harmful effects toward normal cells. Autophagy is a self-protective mechanism in many kinds of tumor cells that respond to anticancer treatment. It is reported that autophagy inhibition could enhance the effects of many kinds of anticancer treatments, including gene therapy. However, whether IL-24 is effective to treat oral squamous cell carcinomas (OSCC) and if autophagy inhibition could improve the anticancer effect of IL-24 towards OSCC is has not been detected.

Methods

MTT assays were carried out to determine the cell proliferation; Transfection was used to gene transfer; Western Blot was performed to detect the protein level of LC3II, P62, Beclin 1, Cleaved caspase-3, β-Tubulin and β-actin; Apoptosis rates and cell cycle alteration were analyzed using flow cytometry; Autophagy induction was confirmed by MDC staining, GFP-LC3 staining and transmission electron microscopy. Amount of IL-24 in the culture medium was quantified by ELISA. Apoptosis in vivo was analyzed by TUNEL assay. HE staining was used to observe the morphology of the samples.

Results

In the present study, we proved that IL-24 have a novel anticancer effect towards KB cells and that autophagy inhibition could improve the anticancer effect of IL-24. IL-24 treated cells showed autophagy characteristics and autophagy inhibition by 3-methyladenine (3-MA) significantly enhanced IL-24-induced apoptosis. Similar results were obtained in the KB cells xenograft tumor model.

Conclusions

These results suggest that the combination of autophagy inhibitors and IL-24 based on the AdLTR₂EF1α-mediated gene transfer could be a promising way to cure OSCC.

Prognostic Role of Circulating Tumor Cells during Induction Chemotherapy Followed by Curative Surgery Combined with Postoperative Radiotherapy in Patients with Locally Advanced Oral and Oropharyngeal Squamous Cell Cancer

Background

The prognostic role of circulating tumor cells (CTCs) after induction chemotherapy using docetaxel, cisplatin and fluorouracil (TPF) prior to surgery and adjuvant (chemo)radiation in locally advanced oral squamous cell cancer (OSCC) was evaluated.

Methods

In this prospective study, peripheral blood samples from 40 patients of the phase II study TISOC-1 (NCT01108042) with OSCC before, during, and after treatment were taken. CTCs were quantified using laser scanning cytometry of anti– epithelial cell adhesion molecule–stained epithelial cells. Their detection was correlated with clinical risk factors, recurrence-free (RFS) and overall survival (OS).

Results

Before starting the treatment CTCs were detected in 32 of 40 patients (80%). The median number at baseline was 3295 CTCs/ml. The median maximal number of CTCs during treatment was 5005 CTCs/ml. There was a significant increase of CTCs before postoperative radiotherapy compared to baseline before 1^st cycle of IC (p = 0.011), 2^nd cycle of IC (p = 0.001), 3^rd cycle of IC (p = 0.004), and before surgery (p = 0.002), but not compared to end of therapy (p = 0.118). CTCs at baseline >median was also associated to risk of recurrence (p = 0.014). Maximal CTCs during therapy >median was more frequently observed in tumors of the oral cavity (p=0.022) and related to higher risk of death during follow-up (p = 0.028). Patients with CTCs at baseline >median value had significant lower RFS than patients with CTCs at baseline <median value (p = 0.025). Patients with maximal CTCs values >median during the complete course of therapy had a significantly lower OS than patients with values <median (p = 0.049). Finally, the multivariate analysis revealed that OS was significantly lower in patients with maximal CTCs during treatment higher than the median value (HR=6.151; CI: 1.244-30.420).

Conclusions

Baseline CTCs and maximal CTCs during therapy both seem to be good prognostic markers for OSCC when treated by TPF induction chemotherapy, surgery, and postoperative (chemo)radiation.

Inhibition of growth and migration of oral and cervical cancer cells by citrus polyphenol

BACKGROUND/PURPOSE

It has been confirmed that polyphenolic compounds present in food have various pharmaceutical functions. The purpose of this study was to evaluate citrus polyphenol (CP) for dental applications. The culture medium with CP was developed to inhibit the proliferation of oral cancer cells. CP could be used as a supplemental compound for topical application for oral cancer patients.

METHODS

In this study, the metabolic activity and cell toxicity of CP (at concentrations of 1%, 0.1%, and 0.01%) for oral and cervical cancer cells were investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and lactate dehydrogenase assays (n = 6). Furthermore, the effects of CP on motilities of oral and cervical cancer cells were also evaluated using a scratch assay model.

RESULTS

We found that the growth of Ca9-22 and HeLa cells on tissue culture polystyrene was greatly inhibited when 1% CP was added to the medium. In addition, significant differences (p < 0.01) in cytotoxicities of oral and cervical cancer cells were observed after 6 days in the culture medium to which 1% CP was added. Furthermore, using a scratch assay model to evaluate the migratory abilities of oral and cervical cancer cells, it was also found that CP could inhibit the migratory abilities of cancer cells.

CONCLUSION

The results confirmed the feasibility of the topical application of CP as a supplemental compound for inhibition of cancer cell proliferation and migration.

MicroRNA expression signature of oral squamous cell carcinoma: functional role of microRNA-26a/b in the modulation of novel cancer pathways

BACKGROUND

MicroRNAs (miRNAs) have been shown to play major roles in carcinogenesis in a variety of cancers. The aim of this study was to determine the miRNA expression signature of oral squamous cell carcinoma (OSCC) and to investigate the functional roles of miR-26a and miR-26b in OSCC cells.

METHODS

An OSCC miRNA signature was constructed by PCR-based array methods. Functional studies of differentially expressed miRNAs were performed to investigate cell proliferation, migration, and invasion in OSCC cells. In silico database and genome-wide gene expression analyses were performed to identify molecular targets and pathways mediated by miR-26a/b.

RESULTS

miR-26a and miR-26b were significantly downregulated in OSCC. Restoration of both miR-26a and miR-26b in cancer cell lines revealed that these miRNAs significantly inhibited cancer cell migration and invasion. Our data demonstrated that the novel transmembrane TMEM184B gene was a direct target of miR-26a/b regulation. Silencing of TMEM184B inhibited cancer cell migration and invasion, and regulated the actin cytoskeleton-pathway related genes.

CONCLUSIONS

Loss of tumour-suppressive miR-26a/b enhanced cancer cell migration and invasion in OSCC through direct regulation of TMEM184B. Our data describing pathways regulated by tumour-suppressive miR-26a/b provide new insights into the potential mechanisms of OSCC oncogenesis and metastasis.