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.     

PTPLAD2 is a tumor suppressor in esophageal squamous cell carcinogenesis

Esophageal squamous cell carcinomas (ESCCs) are highly invasive and have poor prognoses. We investigated the role of PTPLAD2, a protein tyrosine phosphatase-like A domain (PTPLAD) family member, in ESCC carcinogenesis. Survival analysis was performed using patient data. ESCC tissue samples lost PTPLAD2 heterozygosity and had decreased PTPLAD2 expression. Low PTPLAD2 expression and high p-STAT3 correlated with poor prognosis. Overexpression of PTPLAD2 in ESCC cells reduced STAT3 phosphorylation, decreased FoxM1, inhibited proliferation and decreased in mouse xenograft tumor formation. Therefore, PTPLAD2 is a potential tumor suppressor and prognostic indicator that reduces STAT3 phosphorylation. PTPLAD2 is a possible clinical target for ESCC treatment.     

SOX2 modulates alternative splicing in transitional cell carcinoma

Aberrant alternative splicing of key cellular regulators may play a pivotal role in cancer development. To investigate the potential influence of altered alternative splicing on the development of transitional cell carcinoma (TCC), splicing activity in the TCC cell lines TSGH8301 and BFTC905 was examined using the SV40-immortalized uroepithelial cell line SV-HUC-1 as a reference. Our results indicate a significant alteration in splice site selection in the TCC cell lines. By gene expression profiling and subsequent validation, we discovered that sex-determining region Y-box protein 2 (SOX2) is specifically upregulated in BFTC905. Furthermore, ectopic expression of SOX2 modulates alternative splicing of the splicing reporter in vivo. More significantly, using an in vitro pull-down assay, it was found that SOX2 exhibits RNA-binding capability. Our observations suggest that SOX2 modulates alternative splicing by functioning as a splicing factor.     

SUZ12 is a novel putative oncogene promoting tumorigenesis in head and neck squamous cell carcinoma

The suppressor of zest 12 (SUZ12), one of the core polycomb repressive complex 2 (PRC2) components, has increasingly appreciated as a key mediator during human tumorigenesis. However, its expression pattern and oncogenic roles in head and neck squamous cell carcinoma (HNSCC) remain largely unexplored yet. Here, we sought to determine its expression pattern, clinicopathological significance and biological roles in HNSCC. Through data mining and interrogation from multiple publicly available databases, our bioinformatics analyses revealed that SUZ12 mRNA was significantly overexpressed in multiple HNSCC patient cohorts. Moreover, SUZ12 protein was markedly up‐regulated in primary HNSCC samples from our patient cohort as assessed by immunohistochemical staining and its overexpression significantly associated with cervical node metastasis and reduced overall and disease‐free survival. In the 4‐nitroquinoline 1‐oxide (4NQO)‐induced HNSCC mouse model, increased SUZ12 immunostaining was observed along with disease progression from epithelial hyperplasia to squamous cell carcinoma in tongue. Furthermore, shRNA‐mediated SUZ12 knock‐down significantly inhibited cell proliferation, migration and invasion in HNSCC cells, and resulted in compromised tumour growth in vivo. Collectively, our data reveal that SUZ12 might serve as a putative oncogene by promoting cell proliferation, migration and invasion, and also a novel biomarker with diagnostic and prognostic significance for HNSCC.     

食管鳞状细胞癌中SOX2和Slug的表达及与肿瘤出芽之间的关系

目的探讨食管鳞状细胞癌中SOX2、Slug的表达与临床病理参数的关系及两者表达与肿瘤出芽的关系。方法应用免疫组织化学染色方法检测89例食管鳞状细胞癌及癌旁组织中SOX2、Slug的表达及计算食管鳞状细胞癌病例HE切片中肿瘤出芽的数量。分析SOX2、Slug的表达在ESCC侵袭和转移中的临床病理学意义。结果食管鳞状细胞癌中SOX2、Slug的表达率分别为53.93%和68.53%,明显高于癌旁组织SOX2和Slug表达率(31.46%和31.46%);癌组织中肿瘤出芽率为39.32%。SOX2高表达与食管鳞状细胞癌的浸润深度、淋巴结转移及高临床分期有关,Slug高表达与食管鳞状细胞癌的分化程度、浸润深度、淋巴结转移及高临床分期有关。肿瘤出芽发生率与食管鳞状细胞癌的分化程度、浸润深度、淋巴结转移及高临床分期有关。Spearman相关性分析表明,食管鳞状细胞癌组织中SOX2表达与Slug表达呈显著正相关,Slug表达与肿瘤出芽明显呈正相关。结论SOX2的高表达可能通过上调Slug的表达从而促进肿瘤的出芽,在食管鳞状细胞癌的侵袭及转移过程中发挥重要作用。     

Loss of Trop2 promotes carcinogenesis and features of epithelial to mesenchymal transition in squamous cell carcinoma

Trop2, an oncogenic cell surface protein under investigation as a therapeutic target, is commonly overexpressed in several epithelial tumor types yet its function in tumor biology remains relatively unexplored. To investigate the role of Trop2 in epithelial carcinogenesis, we generated Trop2(-/-) mice, which are viable and possess a normal lifespan. Contrary to expectations, Trop2 loss fails to suppress keratinocyte transformation. Instead, ras-transformed Trop2(-/-) keratinocytes preferentially pass through an epithelial to mesenchymal transition (EMT) and form tumors with spindle cell histology. Furthermore, Trop2 loss renders Arf-null mice susceptible to the formation of biphasic sarcomatoid carcinomas containing both squamous and spindle cell components upon carcinogen exposure in an otherwise skin cancer-resistant strain (C57BL/6). Immortalized keratinocytes derived from Trop2(-/-)Arf(-/-) mice exhibit enhanced proliferative and migratory capacity as well as increased activation of mitogen-activated protein kinase and Src prior to transformation. The clinical relevance of these findings was supported by studying the molecular epidemiology of Trop2 in primary head and neck squamous cell carcinomas. This analysis revealed that Trop2 mRNA levels are decreased in a subset of tumors with features of EMT, and total loss of Trop2 protein expression is observed in the spindle cell component of sarcomatoid carcinomas. Therefore, while previous studies have emphasized the potential importance of Trop2 gain of function, these results uncover a role for Trop2 loss in tumorigenesis and the mesenchymal transdifferentiation observed in a subset of squamous cell carcinomas.     

LUCAT1 as an oncogene in tongue squamous cell carcinoma by targeting miR-375 expression

Emerging studies suggested that lncRNAs play a crucial molecular role in cancer development and progression. LncRNA LUCAT1 has been proved as oncogenic molecular in lung cancer, glioma, osteosarcoma, renal carcinoma and oesophageal squamous cell carcinoma. However, its roles and function mechanisms in tongue squamous cell carcinoma (TSCC) are still unknown. We showed that the expression of LUCAT1 was up-regulated in the TSCC cells and tissues and the higher LUCAT1 expression was associated with the poor overall survival (OS). Knockdown expression of LUCAT1 suppressed TSCC cell proliferation, cycle and migration. In addition, we demonstrated that miR-375 overexpression inhibited the luciferase activity of LUCAT1 wild-type and knockdown LUCAT1 promoted the miR-375 expression in TSCC cell. Furthermore, we indicated that miR-375 expression was down-regulated in the TSCC cell lines and tissues and the lower expression of miR-375 was associated with poor OS. The expression of miR-375 was inversely correlated with LUCAT1 expression in the TSCC tissues. Knockdown LUCAT1 promoted TSCC cell proliferation, cell cycle and migration partly through regulating miR-375 expression. In summary, this study suggested the tumorigenic effect of lncRNA LUCAT1 in TSCC cells by targeting miR-375 expression.     

CTTN （EMS1）： an oncogene contributing to the metastasis of esophageal squamous cell carcinoma

Proto-oncogenes are frequently activated by genomicamplification.Characterization of genes with increasedcopy numbers and consequent over-expression in tumortissues can facilitate the identification of tumor-specificoncogenes.Esophageal cancer is a common cancer worldwideand esophageal squamous cell carcinoma(ESCC)is themost prevalent type in China.Multiple genetic changeshave been found in ESCC,but little is known about majoroncogenes and tumor suppressor genes involved in thetumorigenesis of ESCC.As the chromosome locus 11q 13 is frequently amplifiedin ESCC[1,2],Luo et al.[3]examined several cancer-related genes in the 11q13 region,including MYEOV,ORAOV1,FGF19,FGF4,FGF3,ORAOV2,FADD1,PP-FIA1 and CTTN,in primary ESCC and matched normaltissues by RT-PCR.Only the cortactin gene(CTTN,also asEMS1)presented overexpression in most of the examinedtumor tissues.The authors subsequently examined CTTNat the genomic DNA and protein levels.CTTN amplifica-     

AKR1C2 acts as a targetable oncogene in esophageal squamous cell carcinoma via activating PI3K/AKT signaling pathway

The aldo‐keto reductases family 1 member C2 (AKR1C2) has critical roles in the tumorigenesis and progression of malignant tumours. However, it was also discovered to have ambiguous functions in multiple cancers and till present, its clinical significance and molecular mechanism in oesophageal squamous cell carcinoma (ESCC) has been unclear. The aim of this study was to explore the role of AKR1C2 in the tumorigenesis of ESCC. Here, we showed that AKR1C2 expression was found to be up‐regulated in ESCC tissues and was significantly associated with pathological stage, lymph node metastasis and worse outcomes. Functional assays demonstrated that an ectopic expression of AKR1C2 in ESCC cells resulted in increased proliferation, migration and cisplatin resistance, while knockdown led to inversing effects. Bioinformation analyses and mechanistic studies demonstrated that AKR1C2 activated the PI3K/AKT signalling pathway, furthermore, the inhibitor of PI3K or the selective inhibitor of AKR1C2 enzyme activity could reverse the aggressiveness and showed synergistic antitumour effect when combined with cisplatin, both in vitro and in vivo. In conclusion, Our findings revealed that AKR1C2 could function as an oncogene by activating the PI3K/AKT pathway, as a novel prognostic biomarker and/or as a potential therapeutic target to ESCC.     

Porphyromonas gingivalis in oral squamous cell carcinoma: a review

Oral cancer contributes significantly to the global cancer burden. Oral bacteria play an important role in the spread of oral cancer, according to mounting evidence. The most proven instance is the carcinogenic implications of Porphyromonas gingivalis, a key pathogen in chronic periodontitis. It is imperative to understand the pathogenesis of P. gingivalis in OSCC. This review aims to gather and assess scientific shreds of evidence on the involvement of P. gingivalis in the molecular mechanism of oral squamous cell carcinoma.     

IGF2BP2 maybe a novel prognostic biomarker in oral squamous cell carcinoma

Aim: The main of the present study was to investigate the role of insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) in oral squamous cell carcinoma (OSCC) with the overarching of providing new biomarkers or potential therapeutic targets for OSCC.Methods: We combined datasets downloaded from Gene Expression Omnibus (GEO), The Cancer Genome Atlas (TCGA), and samples collected from the clinic to evaluate the expression of IGF2BP2 in OSCC. IGF2BP2 survival analysis was respectively performed based on TCGA, GEO, and clinical samples. Correlations between IGF2BP2 expression and clinicopathological parameters were then analyzed, and signaling pathways associated with IGF2BP2 expression were identified using gene set enrichment analysis (GSEA 4.1.0). Moreover, an IGF2BP2 co-expressed gene network was constructed, followed by gene ontology (GO) functional enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis on IGF2BP2 co-expressed genes. Finally, TIMER and CIBERSORT were used to analyze the correlations among IGF2BP2, IGF2BP2-coexpressed genes, and tumor-infiltrating immune cells (TICs).Results: IGF2BP2 was highly expressed in OSCC and significantly correlated with overall survival of OSCC patients (P<0.01). High IGF2BP2 expression correlated with poor overall survival. The GSEA results showed that cell apoptosis-, tumor-, and immune-related pathways were significantly enriched in samples with high IGF2BP2 expression. Furthermore, GO and KEGG enrichment analyses results of IGF2BP2 co-expressed genes indicated that these genes are mainly associated with immunity/inflammation and tumorigenesis. In addition, IGF2BP2 and its co-expressed genes are associated with TICs (P<0.01).Conclusion: IGF2BP2 may be a potential prognostic biomarker in OSCC and correlates with immune infiltrates.     

E2F modulates keratinocyte squamous differentiation: implications for E2F inhibition in squamous cell carcinoma

E2F regulation is essential for normal cell cycle progression. Therefore, it is not surprising that squamous cell carcinoma cell lines (SCC) overexpress E2F1 and exhibit deregulated E2F activity when compared with normal keratinocytes. Indeed, deliberate E2F1 deregulation has been shown to induce hyperplasia and skin tumor formation. In this study, we report on a dual role for E2F as a mediator of keratinocyte proliferation and modulator of squamous differentiation. Overexpression of E2F isoforms in confluent primary keratinocyte cultures resulted in suppression of differentiation-associated markers. Moreover, we found that the DNA binding domain and the trans-activation domain of E2F1 are important in mediating suppression of differentiation. Use of a dominant/negative form of E2F1 (E2F d/n) found that E2F inhibition alone is sufficient to suppress the activity of proliferation-associated markers but is not capable of inducing differentiation markers. However, if the E2F d/n is expressed in differentiated keratinocytes, differentiation marker activity is further induced, suggesting that E2F may act as a modulator of squamous differentiation. We therefore examined the effects of E2F d/n in a differentiation-insensitive SCC cell line. We found that treatment with the differentiating agent, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), or expression of E2F d/n alone had no effect on differentiation markers. However, a combination of E2F d/n + TPA induced the expression of differentiation markers. Combined, these data indicate that E2F may play a key role in keratinocyte differentiation. These data also illustrate the unique potential of anti-E2F therapies in arresting proliferation and inducing differentiation of SCCs.     

Expression pattern of squamous cell carcinoma antigen in oesophageal dysplasia and squamous cell carcinoma

The aim of the present study was to evaluate the tissue expression of squamous cell carcinoma antigen (SCCA) in oesophageal dysplasia and squamous cell carcinoma (SCC) with reference to its clinico-pathologic and prognostic significance. Immunohistochemistry using SCCA polyclonal antibody was performed on SCCs from 61 surgical oesophagectomies. Fifteen cases of low-grade dysplasia (LGD) and 37 non-coexistent high-grade dysplasia (HGD) were also sampled from these materials, together with sixteen chronic cases of oesophagitis. SCCA immunoreactivity was present in the maturative compartments of all normal epithelia and oesophagitis. LGDs showed no SCCA immunoreactivity in the dysplastic proliferative component but only in the superficial normal layers. In 94.6% of HGDs, no SCCA immunoreactivity was detected throughout the thickness of the epithelium. In SCCs, SCCA expression higher than 25% was found in 54% of cases. SCCA positivity showed an inverse correlation with histological grade, whereas no statistically significant correlation was found with TNM classifications, stage, or survival. SCCA is not expressed in early oesophageal carcinogenesis but, in SCC, it represents an indicator of histologic differentiation. In differentiated SCC, SCCA may represent a negative factor for cancer invasiveness, through inhibition of proteases.     

Activation of multiple oncogene pathways: a model for experimental carcinogenesis

Evidence from experimental animal tumor models suggests that in many instances, the identity and mechanism of activation of cellular oncogenes is a function of both carcinogen and tissue specificity. In addition, the activation of no single oncogene has yet been found to be either sufficient or necessary for tumorigenesis in any particular experimental system. A hypothesis to account for these and other molecular and biological observations of experimental tumorigenesis has been developed. The hypothesis is based on the premise that multiple tissue specific groups or pathways of oncogenes exist in each cell, and that activation of all the oncogenes in any of these alternative pathways leads to transformation. It is assumed that each oncogene (which may be a member of one or more pathways) has a spontaneous and a carcinogen specific probability of activation. The latter value will vary from carcinogen to carcinogen. By modelling the spontaneous and carcinogen specific probabilities of activation of each gene, the number and identity of genes in each pathway, and the number of pathways in a particular cell type, it is possible to calculate the relative potency of carcinogens, the percentage of tumors containing each activated oncogene, the dose-response relationship, and other parameters. Use of this hypothetical model gives results consistent with experimental observations on oncogene activation in carcinogen-induced animal tumors.     

Local interleukin-2 therapy in bovine ocular squamous cell carcinoma

Summary Five cows bearing bovine ocular squamous cell carcinoma (BOSCC) were treated with low doses of recombinant human interleukin-2 (rhIL-2). A dose of 2500 U rhIL-2 was injected intralesionally and another 2500 U were injected into the subparotid regional lymph node once a day during a period of 5 consecutive days. This cycle of 5 days was repeated after an interval of 2 days. Total regression of the tumor was observed in three out of five animals. One cow showed tumor regression (> 80%) accompanied by metastases to the regional lymph node that were observed from the fifth week after the beginning of the treatment. Growth of the tumor of the fifth animal was retarded after treatment. In vitro proliferation of peripheral blood lymphocytes was investigated in two animals and tumor-infiltrating lymphocytes in one animal during incubation in various rhIL-2 concentrations. Cytotoxic activity of both cell populations against P815, Yac-1 and BOSCC-derived cell lines increased during incubation with rhIL-2. Cultured BOSCC-infiltrating lymphocytes showed predominant killing of the BOSCC-derived autologous cell line after 4 weeks of culture. Preliminary phenotype analysis did not give conclusive results with respect to the types of cells responsible for killing.     

SRSF5 functions as a novel oncogenic splicing factor and is upregulated by oncogene SRSF3 in oral squamous cell carcinoma

Alternative splicing of precursor messenger RNA has been increasingly associated with tumorigenesis. The serine/arginine-rich protein (SR) family plays key roles in the regulation of pre-mRNA alternative splicing. Increasing evidence has demonstrated that the SR protein family is involved in tumorigenesis. However, the functions and mechanisms of SR proteins in tumourigenesis remain largely unknown. In the present study, we discovered that serine/arginine-rich splicing factor 5 (SRSF5) is a novel oncogenic splicing factor that is overexpressed in oral squamous cell carcinoma (OSCC) tissues and cells, being crucial for OSCC cell proliferation and tumor formation. Overexpression of SRSF5 transformed immortal rodent fibroblasts to form tumors in nude mice, while downregulation of SRSF5 in oral squamous cell lines retarded cell growth, cell cycle progression, and tumor growth. The expression of SRSF5 is controlled by an autoregulation mechanism. Serine/arginine-rich splicing factor 3 (SRSF3) has been identified as an oncogene. We found that SRSF5 is a novel target of SRSF3. SRSF3 impairs the autoregulation of SRSF5 and promotes SRSF5 overexpression in cancer cells. Altogether, the present study demonstrated that SRSF5 is a novel oncogene that is upregulated by SRSF3 in OSCC cells.