Role of EZH2 in oral squamous cell carcinoma carcinogenesis

Oral squamous cell carcinoma (OSCC) is a common human malignancy with high incidence rate and poor prognosis. Although the polycomb group protein enhancer of zeste homolog 2 (EZH2) plays a crucial role in cell proliferation and differentiation during the occurrence and development progress of several kinds of malignant tumors, the impact of EZH2 on the development and progression of OSCC is unclear. In this study, we demonstrate that EZH2 is overexpressed in OSCC cells and clinical tissue. With in vitro RNAi analysis, we generated stable EZH2 knocking down cell lines from two OSCC cell lines, with two sh-RNAs targeting to EZH2, respectively. We found that knocking down of EZH2 could decrease the proliferation ability and induce apoptosis of OSCC cells. Moreover, we demonstrated that of EZH2 inhibition decreased the migration and metastasis of OSCC cells. In conclusion, the results of the current study demonstrated an association between EZH2 expression and OSCC cell development. We recommend that EZH2 acts as an oncogene and plays an important role in OSCC carcinogenesis.     

SATB2 overexpression promotes oral squamous cell carcinoma progression by up-regulating NOX4

While atypical expression of special AT-rich sequence-binding protein 2 (SATB2) has been approved associated with tumor progression, metastasis and unfavourable prognosis in various carcinomas. However, in oral squamous cell carcinoma (OSCC), both the expressive state and associated functions of SATB2's are still undefined. Here we show that, in clinical samples from a retrospective cohort of 58 OSCC patients, high expression of SATB2 is associated with poor prognosis of OSCC patients. In this study, we investigated SATB2 is highly expressed in OSCC tissues and cell lines, which can promote OSCC cells' proliferation, migration, invasion and tumor growth. According to sequencing results based on previous literature, we identified NOX4 is a bona fide downstream target of SATB2, when it was knockdown, OSCC's proliferation can be partially suppressed. Furthermore, NOX4 knockdown inhibits tumorigenicity, which can be rescued partially by ectopic expression of SATB2 in HNSCC cell line, and vice versa. Collectively, our findings not only indicate overexpression of SATB2 triggers the proliferative, migratory and invasive mechanisms which are important in the malignant phenotype of OSCC, but also identify NOX4 as the downstream gene for SATB2. These findings indicate that SATB2 may play a key role in OSCC tumorigenicity and may be a future target for the development of new therapeutic regimens.     

Monocarboxylate Transporter 4 Facilitates Cell Proliferation and Migration and Is Associated with Poor Prognosis in Oral Squamous Cell Carcinoma Patients

Monocarboxylate transporter 4 (MCT4) is a cell membrane transporter of lactate. Recent studies have shown that MCT4 is over-expressed in various cancers; however, its role in cancer maintenance and aggressiveness has not been fully demonstrated. This study investigated the role of MCT4 in oral squamous cell carcinoma (OSCC), and found that it is highly expressed in OSCC patients by using immunohistochemistry. Moreover, this over-expression of MCT4 was closely associated with tumor size, TNM classification, lymphatic metastasis, distant metastasis and tumor recurrence, and also poor prognosis. To further study mechanisms of MCT4 in vitro, we used small-interfering RNA to silence its expression in OSCC cell lines. The results showed that knock-down of MCT4 decreased cell proliferation, migration, and invasion. The inhibition of proliferation was associated with down-regulation of p-AKT and p-ERK1/2, while decreased cell migration and invasion may be caused by down-regulation of integrin β4-SRC-FAK and MEK-ERK signaling. Together, these findings provide new insight into the critical role of MCT4 in cell proliferation and metastasis in OSCC.     

The promise of stem cell markers in the diagnosis and therapy of epithelial dysplasia and oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most common type of head and neck cancer. Epithelial dysplasia is often initiated in the cells and cell nuclei adjacent to the epithelial cell membrane. Reduced cell–cell adhesions enable cancer cells to detach from the tumor and disseminate to other organs. The mutations in epithelial dysplasia markers such as E‐cadherin and epithelial cell adhesion molecules (CD326) can lead to proliferation, growth and survival of the tumor cells and persistence of numerous malignancies that play a key role in epithelial dysplasia of OSCC. Accordingly, these genes can be considered prognostic markers or potential therapeutic targets for the tailored management of patients with OSCC. The gene expression profile of OSCC stem cells indicates a differential pattern that facilitates establishing a cell signature. Owing to the highly tumorigenic behavior of cancer stem cells and the role of these cells in tumor differentiation, treatment resistance, relapse, and metastasis, we reviewed the role of stem cell markers in epithelial dysplasia and OSCC.     

circ_SEPT9, a newly identified circular RNA,promotes oral squamous cell carcinoma progression through miR‐1225/PKN2 axis

Circular RNAs (circRNAs) represent a newly discovered class of endogenous non‐coding RNAs which are widely expressed and play important roles in disease progression. However, the function of circRNAs in oral squamous cell carcinoma (OSCC) still remains largely unknown. In this research, we found that circ_SEPT9 was highly expressed in OSCC cell lines and tumour tissues. Results showed that circ_SEPT9 promoted OSCC proliferation and tumour growth. And, circ_SEPT9 also enhanced the migration and invasion of OSCC cells. Mechanically, we found that circ_SEPT9 acted as a sponge for miR‐1225 to rescue PKN2 expression in OSCC cells. Inhibition of circ_SEPT9/miR‐1225/PKN2 pathway could effectively block the proliferation and metastasis of OSCC cells. Our study provides strong evidence that circ_SEPT9/miR‐1225/PKN2 axis is a promising target for OSCC treatment.     

Ubiquitin-specific protease 14 promotes radio-resistance and suppresses autophagy in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a common malignant tumor in the world. Radiotherapy is one of the standard therapies for patients with OSCC, but its clinical efficiency is limited due to radioresistance. In this study, we identified a mechanism of such resistance regulated by Ubiquitin-specific protease 14 (USP14). USP14 expression was significantly increased in clinical OSCC tissue samples and cell lines, and OSCC patients with high USP14 expression predicted poor overall survival rate. Additionally, a negative correlation between USP14 and LC3B was observed in patients with OSCC. We then found that irradiation (IR)-reduced cell survival of OSCC cells lines was further decreased when USP14 was knocked down. However, USP14 over-expression significantly promoted the cell viability of OSCC cells after IR treatment. Colony formation analysis confirmed thatafter IR treatment,USP14 knockdown markedly decreased the proliferation of OSCC cells, but over-expressing USP14 significantly up-regulated the proliferative activity of OSCC cells. Furthermore, DNA damage caused by IR was enhanced by USP14 knockdown, while been suppressed in OSCC cells with USP14 over-expression. Additionally, IR-inducedapoptosis was further promoted by USP14 knockdown in OSCC cells, which was, however, significantly abolished by USP14 over-expression.Moreover, our in vivo studies showed that IR-reduced tumor growth and tumor weight were further enhanced by USP14 knockdown in OSCC tumor-bearing nude mice. Finally, we found that USP14 knockdown could promote IR-induced autophagy by increasing LC3BII and γH2AX expression levels in IR-treated OSCC cells. However, this event was markedly abolished by ATG5 knockdown, subsequently restoring the cell proliferation in IR-incubated OSCC cells.Finally, we found that USP14-mediated apoptosis was autophagy-dependent in IR-treated OSCC cells. Taken together, these findings suggested that suppressing USP14 could alleviateradioresistancein OSCC both in vitro and in vivo by inducing apoptosis and autophagy, and thus could be served as a promising therapeutic strategy for OSCC treatment.     

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.Keywords: Oral Squamous Cell Carcinoma, USP7, siRNA, proliferation, invasion     

VEGF-C 在口腔鳞状细胞癌中的表达及其意义

目的:检测血管内皮生长因子-C(VEGF-C)在口腔鳞状细胞癌(鳞癌)和癌旁组织中的表达情况,探讨VEGF-C在口腔鳞癌的增殖、浸润和淋巴转移中的作用。方法:采用免疫组化方法检测60例口腔鳞癌病人癌组织和癌旁组织中VEGF-C的表达,应用图像分析系统进行分析,用Spearman相关分析研究其与病变部位、肿瘤大小、病理分级、临床分期及颈淋巴结转移之间的关系。结果:口腔鳞癌组织VEGF-C的表达明显高于癌旁组织(u=7.747,P<0.01),其表达强度与临床分期及淋巴结转移密切相关(r=0.564、0.706,P<0.05),与病变部位、大小、病理分级无关。结论:口腔鳞癌细胞分泌VEGF-C诱导癌周淋巴管增生扩张是发生区域淋巴结转移的重要因素之一,VEGF-C有望作为早期临床判断和预测颈淋巴结转移的指标之一。     

Toll-like receptor 2 activation implicated in oral squamous cell carcinoma development

Recent studies have revealed that Toll-like receptors (TLRs) are highly expressed and activated in many types of cancer. Physiologically, TLR2 recognizes bacteria and other microorganisms in the oral cavity; however, the role of TLR2 in oral squamous cell carcinoma (OSCC) is unclear. In this study, we demonstrated that TLR2 is highly expressed in OSCC in comparison with adjacent non-malignant tissue. TLR2 was also expressed in OSCC-derived cell lines, and its expression was activated by ligands derived from bacteria and mycoplasma. Furthermore, to elucidate the mechanism of OSCC progression via TLR2 signal transduction, we focused on microRNAs (miRNAs) that are induced by TLR2 activation. Interestingly, ligand activation of TLR2 induced the expression of miR-146a and we found that downregulation of caspase recruitment domain–containing protein 10 (CARD10) mRNA in OSCC-derived cell lines. Moreover, knockdown of CARD10 induced resistance to cisplatin-induced apoptosis in OSCC cells. These findings suggest that the activation of TLR2 by bacterial components can enhance the progression of OSCC and may be implicated in acquired resistance to cisplatin-induced apoptosis through regulation of the miR-146a pathway.     

Expression of Snail is associated with myofibroblast phenotype development in oral squamous cell carcinoma

Snail is a regulator of epithelial–mesenchymal transition (EMT) and considered crucial to carcinoma metastasis, myofibroblast transdifferentiation, and fibroblast activation. To investigate the role of Snail in oral squamous cell carcinoma (OSCC), its immunohistochemical expression was analysed in 129 OSCC samples and correlated to nodal metastasis, histological grade, E-cadherin, and alpha smooth-muscle-actin (αSMA). The results were compared to findings in 23 basal cell carcinomas (BCC). Additionally, the influence of TGFβ1 and EGF on Snail, E-cadherin, vimentin, and αSMA expression was analysed in two OSCC cell lines. As a result, Snail-positive cells were mainly found in the stroma of the OSCC invasive front without statistically significant correlation to histological grade or nodal metastasis. Snail was co-localised to αSMA but not to E-cadherin or cytokeratin and showed a significant correlation to the loss of membranous E-cadherin. All BCCs were Snail negative. In OSCC culture, the growth-factor-mediated EMT-like phenomenon was accompanied by αSMA down-regulation. In summary, Snail expression in OSCC is a stromal phenomenon associated with the myofibroblast phenotype and not related to growth-factor-mediated transdifferentiation of the carcinoma cells themselves. Consequently, Snail immunohistochemistry cannot contribute to the prediction of the metastatic potential. Furthermore, stromal Snail expression is suggested to be the result of mutual paracrine interaction of fibro-/myofibroblasts and dedifferentiated carcinoma cells leading to the generation of a special type of carcinoma-associated fibroblasts. M. Franz and K. Spiegel have contributed equally to the study.     

miR-29a-3p enhances the radiosensitivity of oral squamous cell carcinoma cells by inhibiting ADAM12

Oral squamous cell carcinoma (OSCC) is the most common malignant tumor in the head and neck, and radiotherapy is the main approach for this disease, while irradiation resistance is a huge challenge that influences radiosensitivity. This study aims to determine the role and function of miR-29a-3p and ADAM12 in the radiosensitivity of OSCC cells. The expression pattern of ADAM12 in OSCC cells was searched in TCGA database. The binding of miR-29a-3p and ADAM12 was predicted by Starbase and verified using dual luciferase reporter gene assay. The RNA or protein expressions of miR-29a-3p and ADAM12 were measured by RT-qPCR or western blot. OSCC cell lines were treated by various γ-ray irradiation dosages before the alteration on miR-29a-3p expression and on the cell viability, proliferation, migration and cell apoptosis was detected. ADAM12 was highly expressed in OSCC cells, whose expression in resistant cells was positively correlated with irradiation dosage. Overexpression of ADAM12 in OSCC cells lead to increased cell proliferation and migration ability as well as inhibited cell apoptosis. miRNAs potentially binding ADAM12 in PITA, microT, miRmap and targetscan were screened, among which miR-29a-3p had the maximum differential expression levels in OSCC cells determined by RT-qPCR. Overexpression of miR-29a-3p resulted in suppressed cell viability, proliferation, migration ability and increased cell apoptosis, while this expression pattern can be partially counteracted by ADAM12 overexpression in OSCC cells. miR-29a-3p through targeting and inhibiting AMDM12 enhances the radiosensitivity of OSCC cells.Key words: miR-29a, ADAM12, oral squamous cell carcinoma, radio-resistance, cell viability     

Circular RNA circENTPD7 suppresses the accumulation of PTEN to promote cell proliferation in non-small cell lung cancer

The oncogenic role of circular RNA ENTPD7 (circENTPD7) in cancer biology has been reported in glioblastoma, while its role in non-small cell lung cancer (NSCLC) is unknown. This study was performed to investigate the involvement of circENTPD7 in NSCLC. NSCLC tissues and paired non-tumor tissues were collected from 64 NSCLC patients and the expression of circENTPD7 and PTEN were determined by RT-qPCR. Expression levels of PTEN protein in these tissue samples were measured by ELISA. The 64 NSCLC patients were subjected to a follow-up study to explore the role of circENTPD7 in predicting the survival of NSCLC. Overexpression of circENTPD7 was achieved in NSCLC cells, and the effects of overexpression of circENTPD7 on the expression of PTEN were measured by RT-qPCR and Western blot at mRNA and protein level, respectively. Cell proliferation was assessed by CCK-8 assay. CircENTPD7 was upregulated in NSCLC and high expression levels of circENTPD7 predicts the poor survival rate of NSCLC cells. In NSCLC tissues, circENTPD7 was inversely correlated with PTEN protein but not mRNA. In NSCLC tissues, overexpression of circENTPD7 resulted in downregulation of PTEN, but did not alter the expression of PTEN mRNA. Cell proliferation analysis showed that overexpression of circENTPD7 promoted the proliferation of NSCLC cells and reduced the inhibitory effects of overexpression of PTEN on cell proliferation. CircENTPD7 may suppress the accumulation of PTEN to promote cell proliferation in NSCLC.     

microRNA-1297 involves in the progression of oral squamous cell carcinoma through PTEN

Background

Oral squamous cell carcinoma (OSCC) oncogenic mechanisms still remain elusive. Herein, we proposed to understand the biological role of a newly discovered OSCC miRNA.

NDRG2 is a candidate tumor-suppressor for oral squamous-cell carcinoma

Oral cancer is one of the most common cancers worldwide, and squamous-cell carcinoma (OSCC) is the most common phenotype of oral cancer. Although patients with OSCC have poor survival rates and a high incidence of metastasis, the molecular mechanisms of OSCC development have not yet been elucidated. This study investigated whether N-myc downstream-regulated gene 2 (NDRG2) contributes to the carcinogenesis of OSCC, as NDRG2 is reported to be a candidate tumor-suppressor gene in a wide variety of cancers. The down-regulation of NDRG2 mRNA, which was dependent on promoter methylation, was seen in the majority of OSCC cases and in several cases of precancerous leukoplakia with dysplasia. Induction of NDRG2 expression in an HSC-3/OSCC cell line significantly inhibited cell proliferation and decreased colony formation ability on soft agar. The majority of OSCC cell lines showed an activation of PI3K/Akt signaling, and enforced expression of NDRG2 in HSC-3 cells decreased the level of phosphorylated Akt at Serine 473 (p-Akt). Immunohistochemical p-Akt staining was detected in 56.5% of the OSCC tumors, and 80.4% of the tumors were negative for NDRG2 staining. Moreover, positive p-Akt staining was inversely correlated with decreased NDRG2 expression in OSCC tumors with moderate to poor differentiation (p < 0.005). Therefore, NDRG2 is a candidate tumor-suppressor gene for OSCC development and probably contributes to the tumorigenesis of OSCC partly via the modulation of Akt signaling.     

MiR-34a inhibits the proliferation,migration, and invasion of oral squamous cell carcinoma by directly targeting SATB2

In various kinds of carcinomas, the special AT-rich sequence-binding protein 2 (SATB2) with its atypical expression promotes the metastasis and progression of the tumor, though in the oral squamous cell carcinoma (OSCC) its inherent mechanism and the status of SATB2 remain unclear. The role played by the SATB2 expression in the OSCC cell lines and tissue samples in the target of miR-34a downstream is the intended endeavor of this study. In te OSCCs the miR-34a expression was determined by quantitative real-time polymerase chain reaction (q-PCR), while the SATB2 expression in the cell lines and tissue samples in OSCC was analyzed with the q-PCR and the western blot. Studies in both in vitro and in vivo of the effects of miR-34a on the initiation of OSCC were conducted. As a direct target of the miR-34a the SATB2 was verified with the luciferase reporter assay. In cases where the miR-34a levels were low, the SATB2 in OSCCs seemed to be overexpressed. Besides, both in the in vitro and in vivo a suppression of migration, invasion, and cell growth was caused by miR-34a by down regulating the SATB2 expression. The SATB2 being a direct target of miR-34a was confirmed by the cotransfection of miR-34a mimics specifically the decrease in the expression of luciferase of SATB2–3′UTR-wt reporter. As a whole, our study confirmed the inhibition of miR-34a in the invasion, proliferation, and migration of the OSCCs, playing a potential tumor suppressor role with SATB2 as its downstream target.