Combination of proton- or X-irradiation with anti-PDL1 immunotherapy in two murine oral cancers.

Combining radiation therapy with immunotherapy is a strategy to improve both treatments. The purpose of this study was to compare responses for two syngeneic head and neck cancer (HNC) tumor models in mice following X-ray or proton irradiation with or without immune checkpoint inhibition (ICI). MOC1 (immunogenic) and MOC2 (less immunogenic) tumors were inoculated in the right hind leg of each mouse (C57BL/6J, n = 398). Mice were injected with anti-PDL1 (10 mg/kg, twice weekly for 2 weeks), and tumors were treated with single-dose irradiation (5-30 Gy) with X-rays or protons. MOC2 tumors grew faster and were more radioresistant than MOC1 tumors, and all mice with MOC2 tumors developed metastases. Irradiation reduced the tumor volume in a dose-dependent manner. ICI alone reduced the tumor volume for MOC1 with 20% compared to controls, while no reduction was seen for MOC2. For MOC1, there was a clear treatment synergy when combining irradiation with ICI for radiation doses above 5 Gy and there was a tendency for X-rays being slightly more biologically effective compared to protons. For MOC2, there was a tendency of protons being more effective than X-rays, but both radiation types showed a small synergy when combined with ICI. Although the responses and magnitudes of the therapeutic effect varied, the optimal radiation dose for maximal synergy appeared to be in the order of 10-15 Gy, regardless of tumor model.

Investigation of Roles of SLC38A1 in Proliferation and Differentiation of Mouse Tongue Epithelium and Expression in Human Oral Tongue Squamous Cell Carcinoma.

The aerobic glycolytic pathway, boosting lactate formation, and glutamine addiction are two hallmarks of cancer pathophysiology. Consistent with this, several cell membrane glutamine transporters, belonging to different solute carrier (SLC) families, have been shown to be upregulated in a cell-specific manner to furnish the cells with glutamine and glutamine-derived metabolic intermediates. Among them, the system A transporter Slc38a1 has a higher affinity for glutamine compared to other SLC transporters, and it undergoes highly multifaceted regulation at gene and protein levels. The current study aimed to investigate the functional role of Slc38a1 in the proliferation and maturation of the mouse tongue epithelium. Secondly, we aimed to examine the expression of SLC38A1 and its regulation in human tongue oral squamous cell carcinoma (OTSCC). Employing Slc38a1 wild-type and knockout mice, we showed that Slc38a1 was not directly linked to the regulation of the proliferation and differentiation of the mouse tongue epithelium. External transcriptomic datasets and Western blot analyses showed upregulation of SLC38A1 mRNA/protein in human OTSCC and oral cancer cell lines as compared to the corresponding controls. Further, an investigation of external datasets indicated that mechanisms other than the amplification of the SLC38A1 chromosomal locus or hypomethylation of the SLC38A1 promoter region might be important for the upregulation of SLC38A1 in OTSCC.

An Update on S100A16 in Human Cancer.

S100A16 is a member of the S100 protein family. S100A16 is expressed in a variety of human tissues, although at varying levels. S100A16 expression is especially high in tissues rich in epithelial cells. mRNA and protein levels of S100A16 have been reported to be differentially expressed in the majority of human cancers. Functionally, S100A16 has been linked to several aspects of tumorigenesis, for example, cell proliferation, differentiation, migration, invasion, and epithelial-mesenchymal transition (EMT). Accordingly, S100A16 has been suggested to have both tumour-promoting and suppressive roles in human cancers. S100A16-mediated cellular functions are suggested to be mediated by the regulation of various signaling pathways/proteins including EMT-related proteins E-cadherin and Vimentin, PI3K-AKT, p53, MMP1-1, MMP-2, MMP-9, JNK/p38, etc. In addition to the functional roles, expression of S100A16 has been suggested to have prognostic potential in various cancer types. The aims of this review are to summarise the expression profile, identify common molecular partners and functional roles, and explore the prognostic potential of S100A16 in human cancers.

Investigation of biological effects of HEMA in 3D-organotypic co-culture models of normal and malignant oral keratinocytes.

Several in vitro studies utilizing 2-dimensional (2D) cell culture systems have linked 2-hydroxyethyl methacrylate (HEMA) with cytotoxic effects in oral mucosa and dental pulp cells. Although such studies are invaluable in dissecting the cellular and molecular effects of HEMA, there is a growing interest in the utilization of appropriate 3-dimensional (3D) models that mimic the structure of oral mucosa. Using a previously characterized 3D-organotypic co-culture model, this study aimed to investigate the cellular and molecular effects of HEMA on a 3D-co-culture model consisting of primary normal oral keratinocyte (NOK) grown directly on top of collagen I gel containing primary oral fibroblasts (NOF). The second aim was to examine the suitability of a 3D-co-culture system consisting of oral squamous cell carcinoma (OSCC) cells as a model system to investigate the biological effects of HEMA. We demonstrated that HEMA treatment led to reduced viability of NOK, NOF and OSCC-cell lines in 2D-culture. The keratinocytes in 3D-co-cultures of NOK and OSCC-cells reacted similarly with respect to cell proliferation and activation of autophagy flux, to HEMA treatment. Nevertheless, NOK was found to be more susceptible to apoptosis following HEMA treatment than OSCC in 3D-co-cultures. These results indicate that 3D-organotypic co-cultures of NOK might represent an appropriate model system for the investigation of the biological effects of HEMA and other dental biomaterials. Given the challenges in obtaining primary cultures of NOK and issues associated with their rapid differentiation in culture, the possible use of OSCC cells as an alternative to NOK for 3D models represents an area for future research.

High-risk human papilloma virus was not detected in a Norwegian cohort of oral squamous cell carcinoma of the mobile tongue.

OBJECTIVES: The presence of and the causative role of high-risk human papilloma virus (HPV) is a subject of controversy in oral squamous cell carcinoma (OSCC). The disagreement can be related to the misclassification of OSCC as oropharyngeal squamous cell carcinoma and/or lack of standard detection methods. This study aimed to examine the presence of transcriptionally active high-risk HPV in a homogenous Norwegian cohort of primary and second primary OSCC of the mobile tongue (oral tongue squamous cell carcinoma-OTSCC). METHODS: Tissue microarrays containing formalin-fixed and paraffin-embedded cores of 146 OTSCC from the anterior 2/3 of the tongue (n = 128 primary and n = 18 second primary) from a multicentric Norwegian cohort were examined for the presence of high-risk HPV by DNA- and RNA-in situ hybridization (ISH) assays and p16 immunohistochemistry. RESULTS: Transcriptionally active HPV (E6/E7 mRNA) was not identified in any of the OTSCC specimens. In parallel, no tumors were positive for HPV by DNA ISH. Although, 61 (42%) OTSCC demonstrated p16 positivity with varying staining intensity and subcellular localization, only two cases demonstrated strong and uniform p16-staining (both cytoplasmic and nuclear) in >70% of cancer cells. The absence of transcriptionally active high-risk HPV in this cohort of OTSCC indicates that high-risk HPV is an unlikely causative factor in the present material.