Epithelial to mesenchymal transition (EMT) contributes to tumor progression, cancer cell invasion, and therapy resistance. EMT is regulated by transcription factors such as the protein products of the SNAI gene family, which inhibits the expression of epithelial genes. Several signaling pathways, such as TGF-beta1, IL-6, Akt, and Erk1/2, trigger EMT responses. Besides regulatory transcription factors, RNA molecules without protein translation, micro RNAs, and long non-coding RNAs also assist in the initialization of the EMT gene cluster. A challenging novel aspect of EMT research is the investigation of the interplay between tumor microenvironments and EMT. Several microenvironmental factors, including fibroblasts and myofibroblasts, as well as inflammatory, immune, and endothelial cells, induce EMT in tumor cells. EMT tumor cells change their adverse microenvironment into a tumor friendly neighborhood, loaded with stromal regulatory T cells, exhausted CD8⁺ T cells, and M2 (protumor) macrophages. Several EMT inhibitory mechanisms are instrumental in reversing EMT or targeting EMT cells. Currently, these mechanisms are also significant for clinical use.

Fibroblasts (Fibs) contribution to neoplastic progression, tumor growth, angiogenesis, and metastasis has been recently reported by several research groups. In this study it was investigated if fibroblasts are the source of brain-derived neurotrophic factor (BDNF), which plays a crucial role in the progression of oral squamous cell carcinoma. In a novel in vitro system oral Fibs were cultured with SCC-25 lingual squamous cell carcinoma cells for 7days. Factors related with this interaction were investigated by quantitative PCR and western blot. In the co-culture, fibroblasts were converted to carcinoma-associated fibroblasts (CAFs), which in return initiated epithelial-mesenchymal transition (EMT) of SCC-25 cells. The induced CAFs produced increased levels of BDNF, which interacted with the increased-expressed neurothrophin receptor B (TrkB) on EMT-converted SCC-25 cells. Possible regulatory factors of BDNF expression (tumor necrosis factor-α and interleukin-1-β) were detected both in CAFs and EMT-tumor cells. In CAFs: IL-1β-, in SCC-25 cells TNF-α-gene-expression was significantly increased in co-culture conditions. Activated fibroblasts (CAFs) and mesenchymal transitioned tumor cells might use the BDNF-TrkB axis and its regulation to harmonize their interaction in the process of tumor progression.

Photodynamic therapy (PDT) is suggested to have an impact on the treatment of early stage head and neck cancers (HNSCC). We investigated the effect of PDT with methylene blue (MB) and a diode laser (660 nm) as the laser source on HNSCC cell lines as an in vitro model of surface oral squamous cell carcinoma. Cell-cultures were exposed to 160 µM MB for 4 min and to laser light for 8 min. Viability was proven via cell viability assay and clonogenic survival via clone counting assay. The combination of MB and diode laser evidenced high efficient loss of cell viability by 5% of the control, while treatment with the same concentration of MB for 4 min alone showed a viability of 46% of the control. In both SCC-25 and Detroit 562 HNSCC cells, MB combined with the laser allowed a significant abrogation of clonogenic growth (p < 0.01), especially in the case of Detroit 562 cells less than 1% of the suspension plated cells were able to grow tumor cell nests. Multiresistant (Detroit 562) HNSCC cells expressing cancer stem cell markers are sensitive to MB/red laser combined PDT.

Co-culture of periodontal ligament (PDL) fibroblasts and SCC-25 oral squamous carcinoma cells (OSCC), results in conversion of PDLs into carcinoma-associated fibroblasts (CAFs). Paracrin circuits between CAFs and OSCC cells were hypothesized to regulate the gene expression of matrix remodeling enzymes in their co-culture, which was performed for 7days, followed by analysis of the mRNA/protein expression and activity of metalloproteinases (MMPs), their tissue inhibitors (TIMPs) and other relevant genes. Interleukin1-β, transforming growth factor-β1, fibronectin and αvβ6 integrin have shown to be involved in the regulation of the MMP and TIMP gene expression in co-culture of CAFs and tumor cells. In addition, these cells also cooperated in activation of MMP pro-enzymes. It is particularly interesting that the fibroblast-produced inactive MMP-2 has been activated by the tumor-cell-produced membrane-type 1 matrix metalloproteinase (MT1-MMP). The crosstalk between cancer- and the surrounding fibroblast stromal-cells is essential for the fine tuning of cancer cells invasivity.

With the increase in long-term survivorship of head and neck cancer (HNC), the functional outcomes are gaining importance. We reported the functional outcomes of HNC patients using the HNC-Functional InTegrity (FIT) Scales, which is a validated tool for the rapid clinical assessment of functional status based on observable clinical criteria. Patients with newly diagnosed HNC treated at the Medical University of Innsbruck between 2008 and 2020 were consecutively included, and their status in the six functional domains of food-intake, breathing, speech, pain, mood, and neck and shoulder mobility was scored by the treating physician at oncological follow-up visits on a scale from 0 (loss of function) to 4 (full function). HNC-FIT scales were available for 681 HNC patients at a median of 35 months after diagnosis. The response status was complete remission in 79.5%, 18.1% had recurrent or persistent disease, and 2.4% had a second primary HNC. Normal or near-normal scores (3 and 4) were seen in 78.6% for food intake, 88.7% for breathing, 83.7% for speech, 89% for pain, 91.8% for mood, and 87.5% for neck and shoulder mobility. A normal or near-normal outcome in all six functional domains was observed in 61% of patients. Clinically relevant impairment (score 1–2) in at least one functional domain was observed in 30%, and 9% had loss of function (score 0) in at least one functional domain. The main factors associated with poor functional outcome in a multivariable analysis were recurrence or persistent disease, poor general health (ASA III and IV), and higher T stage. Particularly, laryngeal and hypopharyngeal tumors impaired breathing and speech function, and primary radiation therapy or concomitant systemic therapy and radiotherapy worsened food intake. Clinically relevant persistent functional deficits in at least one functional domain must be expected in 40% of the patients with HNC. The treatment of these functional deficits is an essential task of oncologic follow-up.

Recently we described a co-culture model of periodontal ligament (PDL) fibroblasts and SCC-25 lingual squamous carcinoma cells, which resulted in conversion of normal fibroblasts into carcinoma-associated fibroblasts (CAFs), and in epithelial-mesenchymal transition (EMT) of SCC-25 cells. We have found a constitutive high interleukin-1β (IL1-β) expression in SCC-25 cells in normal and in co-cultured conditions. In our hypothesis a constitutive IL1-β expression in SCC-25 regulates gene expression in fibroblasts during co-culture. Co-cultures were performed between PDL fibroblasts and SCC-25 cells with and without dexamethasone (DEX) treatment; IL1-β processing was investigated in SCC-25 cells, tumor cells and PDL fibroblasts were treated with IL1-β. IL1-β signaling was investigated by western blot and immunocytochemistry. IL1-β-regulated genes were analyzed by real-time qPCR. SCC-25 cells produced 16kD active IL1-β, its receptor was upregulated in PDL fibroblasts during co-culture, which induced phosphorylation of interleukin-1 receptor-associated kinase-1 (IRAK-1), and nuclear translocalization of NFκBα. Several genes, including interferon regulatory factor 1 (IRF1) interleukin-6 (IL-6) and prostaglandin-endoperoxide synthase 2 (COX-2) were induced in CAFs during co-culture. The most enhanced induction was found for IL-6 and COX-2. Treatment of PDL fibroblasts with IL1-β reproduced a time- and dose-dependent upregulation of IL1-receptor, IL-6 and COX-2. A further proof was achieved by DEX inhibition for IL1-β-stimulated IL-6 and COX-2 gene expression. Constitutive expression of IL1-β in the tumor cells leads to IL1-β-stimulated gene expression changes in tumor-associated fibroblasts, which are involved in tumor progression.