MicroRNA alterations and associated aberrant DNA methylation patterns across multiple sample types in oral squamous cell carcinoma

Background

MicroRNA (miRNA) expression is broadly altered in cancer, but few studies have investigated miRNA deregulation in oral squamous cell carcinoma (OSCC). Epigenetic mechanisms are involved in the regulation of >30 miRNA genes in a range of tissues, and we aimed to investigate this further in OSCC.

Methods

TaqMan® qRT-PCR arrays and individual assays were used to profile miRNA expression in a panel of 25 tumors with matched adjacent tissues from patients with OSCC, and 8 control paired oral stroma and epithelium from healthy volunteers. Associated DNA methylation changes of candidate epigenetically deregulated miRNA genes were measured in the same samples using the MassArray® mass spectrometry platform. MiRNA expression and DNA methylation changes were also investigated in FACS sorted CD44^high oral cancer stem cells from primary tumor samples (CSCs), and in oral rinse and saliva from 15 OSCC patients and 7 healthy volunteers.

Results

MiRNA expression patterns were consistent in healthy oral epithelium and stroma, but broadly altered in both tumor and adjacent tissue from OSCC patients. MiR-375 is repressed and miR-127 activated in OSCC, and we confirm previous reports of miR-137 hypermethylation in oral cancer. The miR-200 s/miR-205 were epigenetically activated in tumors vs normal tissues, but repressed in the absence of DNA hypermethylation specifically in CD44^high oral CSCs. Aberrant miR-375 and miR-200a expression and miR-200c-141 methylation could be detected in and distinguish OSCC patient oral rinse and saliva from healthy volunteers, suggesting a potential clinical application for OSCC specific miRNA signatures in oral fluids.

Conclusions

MiRNA expression and DNA methylation changes are a common event in OSCC, and we suggest miR-375, miR-127, miR-137, the miR-200 family and miR-205 as promising candidates for future investigations. Although overall activated in OSCC, miR-200/miR-205 suppression in oral CSCs indicate that cell specific silencing of these miRNAs may drive tumor expansion and progression.     

A Novel Compound NSC745885 Exerts an Anti-Tumor Effect on Tongue Cancer SAS Cells In Vitro and In Vivo

Objective

Oral squamous cell carcinoma (OSCC) is a prevalent cancer, especially in developing countries. Anthracyclines and their anthraquinone derivatives, such as doxorubicin, exhibit a cell growth inhibitory effect and have been used as anti-cancer drugs for many years. However, the cardiotoxicity of anthracycline antibiotics is a major concern in their clinical application. NSC745885 is a novel compound synthesized from 1,2-diaminoanthraquinone, which subsequently reacts with thionyl chloride and triethylamine. The present study aimed to investigate the anti-oral cancer potential and the safety of NSC745885.

Methods

We investigated the anti-cancer potential of NSC745885 in oral squamous carcinoma cell lines and in an in vivo oral cancer xenograft mouse model. The expression of apoptotic related genes were evaluated by real-time RT-PCR and western bloting, and the in vivo assessment of apoptotic marker were measured by immunohistochemical staining. The anti-tumor efficiency and safety between doxorubicin and NSC745885 were also compared.

Results

Our results demonstrated that NSC745885 exhibits anti-oral cancer activity through the induction of apoptosis in cancer cells and in tumor-bearing mice, and this treatment did not induce marked toxicity in experimental mice. This compound also exhibits a comparable anti-tumor efficiency and a higher safety in experimental mice when compared to doxorubicin.

Conclusions

The data of this study provide evidence for NSC745885 as a potential novel therapeutic drug for the treatment of human OSCC.     

USP22 Is Useful as a Novel Molecular Marker for Predicting Disease Progression and Patient Prognosis of Oral Squamous Cell Carcinoma

Background and Objective

The significance of ubiquitin-specific protease 22 (USP22) as a potential marker has been growing in the field of oncology. The aim of this study was to investigate the role of USP22 and the association with its potential targets in oral squamous cell carcinoma (OSCC).

Methods

Immunohistochemistry was used to determine the expression of USP22 protein in 319 OSCC patients in comparison with 42 healthy controls. The clinical correlations and prognostic significance of the aberrantly expressed protein was evaluated to identify novel biomarker of OSCC.

Results

The incidence of positive USP22 expression was 63.32% in 319 conventional OSCC tissues. The protein expression level of USP22 was concomitantly up-regulated from non-cancerous mucosa to primary carcinoma and from carcinomas to lymph node metastasis (P<0.001). Moreover, statistical analysis showed that positive USP22 expression was positively related to lymph node metastasis, Ki67, Cox-2 and recurrence. Furthermore, it was shown that patients with positive USP22 expression had significantly poorer outcome compared with patients with negative expression of USP22 for patients with positive lymph nodes. Multivariate Cox regression analysis revealed that USP22 expression level was an independent prognostic factor for both overall survival and disease-free survival (P<0.001 and P<0.001, respectively). Cancer cells with reduced USP22 expression exhibited reduced proliferation and colony formation evaluated by MTT and soft agar assays.

Conclusion

To our knowledge, this is the first study that determines the relationship between USP22 expression and prognosis in OSCC. We found that increased expression of USP22 is associated with poor prognosis in OSCC. USP22 may represent a novel and useful prognostic marker for OSCC.     

Tumour Microenvironments Induce Expression of Urokinase Plasminogen Activator Receptor (uPAR) and Concomitant Activation of Gelatinolytic Enzymes

Background

The urokinase plasminogen activator receptor (uPAR) is associated with poor prognosis in oral squamous cell carcinoma (OSCC), and increased expression of uPAR is often found at the invasive tumour front. The aim of the current study was to elucidate the role of uPAR in invasion and metastasis of OSCC, and the effects of various tumour microenvironments in these processes. Furthermore, we wanted to study whether the cells’ expression level of uPAR affected the activity of gelatinolytic enzymes.

Methods

The Plaur gene was both overexpressed and knocked-down in the murine OSCC cell line AT84. Tongue and skin tumours were established in syngeneic mice, and cells were also studied in an ex vivo leiomyoma invasion model. Soluble factors derived from leiomyoma tissue, as well as purified extracellular matrix (ECM) proteins, were assessed for their ability to affect uPAR expression, glycosylation and cleavage. Activity of gelatinolytic enzymes in the tissues were assessed by in situ zymography.

Results

We found that increased levels of uPAR did not induce tumour invasion or metastasis. However, cells expressing low endogenous levels of uPAR in vitro up-regulated uPAR expression both in tongue, skin and leiomyoma tissue. Various ECM proteins had no effect on uPAR expression, while soluble factors originating from the leiomyoma tissue increased both the expression and glycosylation of uPAR, and possibly also affected the proteolytic processing of uPAR. Tumours with high levels of uPAR, as well as cells invading leiomyoma tissue with up-regulated uPAR expression, all displayed enhanced activity of gelatinolytic enzymes.

Conclusions

Although high levels of uPAR are not sufficient to induce invasion and metastasis, the activity of gelatinolytic enzymes was increased. Furthermore, several tumour microenvironments have the capacity to induce up-regulation of uPAR expression, and soluble factors in the tumour microenvironment may have an important role in the regulation of posttranslational modification of uPAR.     

The Zinc Transporter SLC39A13/ZIP13 Is Required for Connective Tissue Development; Its Involvement in BMP/TGF-β Signaling Pathways

Background

Zinc (Zn) is an essential trace element and it is abundant in connective tissues, however biological roles of Zn and its transporters in those tissues and cells remain unknown.

Methodology/Principal Findings

Here we report that mice deficient in Zn transporter Slc39a13/Zip13 show changes in bone, teeth and connective tissue reminiscent of the clinical spectrum of human Ehlers-Danlos syndrome (EDS). The Slc39a13 knockout (Slc39a13-KO) mice show defects in the maturation of osteoblasts, chondrocytes, odontoblasts, and fibroblasts. In the corresponding tissues and cells, impairment in bone morphogenic protein (BMP) and TGF-β signaling were observed. Homozygosity for a SLC39A13 loss of function mutation was detected in sibs affected by a unique variant of EDS that recapitulates the phenotype observed in Slc39a13-KO mice.

Conclusions/Significance

Hence, our results reveal a crucial role of SLC39A13/ZIP13 in connective tissue development at least in part due to its involvement in the BMP/TGF-β signaling pathways. The Slc39a13-KO mouse represents a novel animal model linking zinc metabolism, BMP/TGF-β signaling and connective tissue dysfunction.     

Near Infrared Imaging of EGFR of Oral Squamous Cell Carcinoma in Mice Administered Arsenic Trioxide

Background

The effectiveness of near-infrared imaging (NIR) interrogation of epidermal growth factor receptor (EGFR) expression as a sensitive biomarker of oral squamous cell carcinoma (OSCC) response to arsenic trioxide therapy was studied in mice.

Material and Methods

A431 OSCC in vitro were exposed to 0 µM, 0.5 µM, 2.5 µM, or 5 µM of As₂O₃ for 0 h, 24 h, 48 h and 72 h. Confocal microscopy and flow cytometry confirmed EGFR expression and demonstrated a sensitivity dose-related signal decline with As₂O₃ treatment. Next, mice with pharynx-implanted A431 cells received As₂O₃ i.p. every 48 h at 0.0, 0.5, 2.5, or 5 mg/kg/day (n = 6/group) from day 0 to 10. An intravenous NIR probe, EGF-Cy5.5, was injected at baseline and on days 4, 8, and 12 for dynamic NIR imaging. Tumor volume and body weights were measured three times weekly.

Results

In vitro, A431 EGFR expression was well appreciated in the controls and decreased (p<0.05) with increasing As₂O₃ dose and treatment duration. In vivo EGFR NIR tumor signal intensity decreased (p<0.05) in As₂O₃ treated groups versus controls from days 4 to 12, consistent with increasing dosage. Tumor volume diminished in a dose-related manner while body weight was unaffected. Immunohistochemical staining of excised tumors confirmed that EGFR expression was reduced by As₂O₃ treatment in a dose responsive pattern.

Conclusion

This study demonstrates for the first time that OSCC can be interrogated in vivo by NIR molecular imaging of the EGFR and that this biomarker is effective for the longitudinal assessment of OSCC response to As₂O₃ treatment.     

The spinal cord expression of neuronal and inducible nitric oxide synthases and their contribution in the maintenance of neuropathic pain in mice

Background

Nitric oxide generated by neuronal (NOS1), inducible (NOS2) or endothelial (NOS3) nitric oxide synthases contributes to pain processing, but the exact role of NOS1 and NOS2 in the maintenance of chronic peripheral neuropathic pain as well as the possible compensatory changes in their expression in the spinal cord of wild type (WT) and NOS knockout (KO) mice at 21 days after total sciatic nerve ligation remains unknown.

Methodology/Principal Findings

The mechanical and thermal allodynia as well as thermal hyperalgesia induced by sciatic nerve injury was evaluated in WT, NOS1-KO and NOS2-KO mice from 1 to 21 days after surgery. The mRNA and protein levels of NOS1, NOS2 and NOS3 in the spinal cord of WT and KO mice, at 21 days after surgery, were also assessed. Sciatic nerve injury led to a neuropathic syndrome in WT mice, in contrast to the abolished mechanical allodynia and thermal hyperalgesia as well as the decreased or suppressed thermal allodynia observed in NOS1-KO and NOS2-KO animals, respectively. Sciatic nerve injury also increases the spinal cord expression of NOS1 and NOS2 isoforms, but not of NOS3, in WT and NOS1-KO mice respectively. Moreover, the presence of NOS2 is required to increase the spinal cord expression of NOS1 whereas an increased NOS1 expression might avoid the up-regulation of NOS2 in the spinal cord of nerve injured WT mice.

Conclusions/Significance

These data suggest that the increased spinal cord expression of NOS1, regulated by NOS2, might be responsible for the maintenance of chronic peripheral neuropathic pain in mice and propose these enzymes as interesting therapeutic targets for their treatment.     

Quercetin Suppresses Drug-Resistant Spheres via the p38 MAPK–Hsp27 Apoptotic Pathway in Oral Cancer Cells

Background

Treatment failure in oral squamous cell carcinoma (OSCC) leading to local recurrence(s) and metastases is mainly due to drug resistance. Cancer stem cells (CSCs) are thought be responsible for the development of drug resistance. However, the correlations between CSCs, drug resistance, and new strategy against drug resistance in OSCC remain elusive.

Methods

A drug-resistant sphere (DRSP) model was generated by using a nonadhesive culture system to induce drug-resistant cells from SCC25 oral cancer cells. A comparative analysis was performed between the parent control cells and DRSPs with a related treatment strategy focusing on the expression of epithelial–mesenchymal transition (EMT)-associated markers, drug-resistance-related genes, and CSC properties in vitro, as well as tumorigenicity and the regimen for tumor regression in vivo.

Results

Our data show the presence of a phenomenon of EMT with gradual cellular transition from an epithelioid to mesenchymal-like spheroid morphology during induction of drug resistance. The characterization of DRSPs revealed the upregulation of the drug-resistance-related genes ABCG2 and MDR-1 and of CSC-representative markers, suggesting that DRSPs have greater resistance to cisplatin (Cis) and stronger CSC properties compared with the control. Moreover, overexpression of phosphorylated heat-shock protein 27 (p-Hsp27) via the activation of p38 MAPK signaling was observed in DRSPs. Knockdown of Hsp27 decreased Cis resistance and induced apoptosis in DRSPs. Furthermore, an inhibitor of Hsp27, quercetin (Qu), suppressed p-Hsp27 expression, with alterations of the EMT signature, leading to the promotion of apoptosis in DRSPs. A xenographic study also confirmed the increase of tumorigenicity in DRSPs. The combination of Qu and Cis can reduce tumor growth and decrease drug resistance in OSCC.

Conclusions

The p38 MAPK–Hsp27 axis plays an important role in CSCs-mediated drug resistance in OSCC. Targeting this axis using Qu combined with Cis may be a treatment strategy to improve prognosis in patients with OSCC.     

Neuropilin-1 Promotes Epithelial-to-Mesenchymal Transition by Stimulating Nuclear Factor-Kappa B and Is Associated with Poor Prognosis in Human Oral Squamous Cell Carcinoma

Background

The epithelial-to-mesenchymal transition (EMT) is a key process in carcinogenesis, invasion, and metastasis of oral squamous cell carcinoma (OSCC). In our previous studies, we found that neuropilin-1 (NRP1) is overexpressed in tongue squamous cell carcinoma and that this overexpression is associated with cell migration and invasion. Nuclear factor-kappa B (NF-κB) plays an essential role both in the induction and the maintenance of EMT and tumor metastasis. Therefore, we hypothesized that NRP1 induces EMT, and that NRP1-induced migration and invasion may be an important mechanism for promoting invasion and metastasis of OSCC through NF-κB activation.

Methods/Results

The variations in gene and protein expression and the changes in the biological behavior of OSCC cell lines transfected with a vector encoding NRP1, or the corresponding vector control, were evaluated. NRP1 overexpression promoted EMT and was associated with enhanced invasive and metastatic properties. Furthermore, the induction of EMT promoted the acquisition of some cancer stem cell (CSC)-like characteristics in OSCC cells. We addressed whether selective inhibition of NF-κB suppresses the NRP1-mediated EMT by treating cells with pyrrolidinedithiocarbamate ammonium (PDTC), an inhibitor of NF-κB. Immunohistochemical analysis of NRP1 in OSCC tissue samples further supported a key mediator role for NRP1 in tumor progression, lymph node metastasis, and indicated that NRP1 is a predictor for poor prognosis in OSCC patients.

Conclusion

Our results indicate that NRP1 may regulate the EMT process in OSCC cell lines through NF-κB activation, and that higher NRP1 expression levels are associated with lymph node metastasis and poor prognosis in OSCC patients. Further investigation of the role of NRP1 in tumorigenesis may help identify novel targets for the prevention and therapy of oral cancers.     

Overexpression of LIM and SH3 Protein 1 Leading to Accelerated G2/M Phase Transition Contributes to Enhanced Tumourigenesis in Oral Cancer

Background

LIM and SH3 protein 1 (LASP-1) is a specific focal adhesion protein involved in several malignant tumors. However, its role in oral squamous cell carcinoma (OSCC) is unknown. The aim of this study was to characterize the role and molecular status/mechanism of LASP-1 in OSCC.

Methods

We evaluated LASP-1 mRNA and protein expressions in OSCC-derived cell lines and primary OSCCs. Using an shRNA system, we analyzed the effect of LASP-1 on the biology and function of the OSCC cell lines, HSC-3 and Ca9-22. The cells also were subcutaneously injected to evaluate tumor growth in vivo. Data were analyzed by the Fisher’s exact test or the Mann-Whitney U test. Bonferroni correction was used for multiple testing.

Results

Significant up-regulation of LASP-1 was detected in OSCC-derived cell lines (n = 7, P<0.007) and primary OSCCs (n = 50, P<0.001) compared to normal controls. LASP-1 knockdown cells significantly inhibited cellular proliferation compared with shMock-transfected cells (P<0.025) by arresting cell-cycle progression at the G2 phase. We observed dramatic reduction in the growth of shLASP-1 OSCC xenografts compared with shMock xenografts in vivo.

Conclusion

Our results suggested that overexpression of LASP-1 is linked closely to oral tumourigenicity and further provide novel evidence that LASP-1 plays an essential role in tumor cellular growth by mediating G2/M transition.     

Genetic-background modulation of core and variable autistic-like symptoms in Fmr1 knock-out mice

Background

No animal models of autism spectrum disorders (ASD) with good construct validity are currently available; using genetic models of pathologies characterized by ASD-like deficits, but with known causes, may be therefore a promising strategy. The Fmr1-KO mouse is an example of this approach, modeling Fragile X syndrome, a well-known genetic disorder presenting ASD symptoms. The Fmr1-KO is available on different genetic backgrounds (FVB versus C57BL/6), which may explain some of the conflicting results that have been obtained with these mutants up till now.

Methods

Fmr1 KO and their wild-type littermates on both the FVB and C57BL/6 genetic backgrounds were examined on a battery of tests modeling the clinical symptoms of ASD, including the triad of core symptoms (alterations in social interaction and communication, presence of repetitive behaviors), as well as the secondary symptoms (disturbances in sensori-motor reactivity and in circadian patterns of activity, epileptic events).

Results

Fmr1-KO mice displayed autistic-like core symptoms of altered social interaction and occurrence of repetitive behaviors with additional hyperactivity. The genetic background modulated the effects of the Fmr1 deletion and it appears that the C57BL/6 background may be more suitable for further research on core autistic-like symptoms.

Conclusions

The Fmr1-mouse line does not recapitulate all of the main core and secondary ASD symptoms, but still can be useful to elucidate the neurobiological mechanisms underlying specific ASD-like endophenotypes.     

Role of serine racemase in behavioral sensitization in mice after repeated administration of methamphetamine

Background

The N-methyl-D-aspartate (NMDA) receptors play a role in behavioral abnormalities observed after administration of the psychostimulant, methamphetamine (METH). Serine racemase (SRR) is an enzyme which synthesizes D-serine, an endogenous co-agonist of NMDA receptors. Using Srr knock-out (KO) mice, we investigated the role of SRR on METH-induced behavioral abnormalities in mice.

Methodology/Principal Findings

Evaluations of behavior in acute hyperlocomotion, behavioral sensitization, and conditioned place preference (CPP) were performed. The role of SRR on the release of dopamine (DA) in the nucleus accumbens after administration of METH was examined using in vivo microdialysis technique. Additionally, phosphorylation levels of ERK1/2 proteins in the striatum, frontal cortex and hippocampus were examined using Western blot analysis. Acute hyperlocomotion after a single administration of METH (3 mg/kg) was comparable between wild-type (WT) and Srr-KO mice. However, repeated administration of METH (3 mg/kg/day, once daily for 5 days) resulted in behavioral sensitization in WT, but not Srr-KO mice. Pretreatment with D-serine (900 mg/kg, 30 min prior to each METH treatment) did not affect the development of behavioral sensitization after repeated METH administration. In the CPP paradigm, METH-induced rewarding effects were demonstrable in both WT and Srr-KO mice. In vivo microdialysis study showed that METH (1 mg/kg)-induced DA release in the nucleus accumbens of Srr-KO mice previously treated with METH was significantly lower than that of the WT mice previously treated with METH. Interestingly, a single administration of METH (3 mg/kg) significantly increased the phosphorylation status of ERK1/2 in the striatum of WT, but not Srr-KO mice.

Conclusions/Significance

These findings suggest first, that SRR plays a role in the development of behavioral sensitization in mice after repeated administration of METH, and second that phosphorylation of ERK1/2 by METH may contribute to the development of this sensitization as seen in WT but not Srr-KO mice.