Concomitant chemoradiotherapy is a common treatment for advanced head and neck squamous cell carcinomas (HNSCC). Cisplatin is the backbone of chemotherapy regimens used to treat HNSCC. Therefore, the aim of this study was to identify predictive markers for cisplatin treatment outcome in HNSCC. The intrinsic cisplatin sensitivity (ICS) was determined in a panel of tumour cell lines. From this panel, one sensitive and two resistant cell lines were selected for comparative transcript profiling using microarray analysis. The enrichment of Gene Ontology (GO) categories in sensitive versus resistant cell lines were assessed using the Gene Ontology Tree Machine bioinformatics tool. In total, 781 transcripts were found to be differentially expressed and 11 GO categories were enriched. Transcripts contributing to this enrichment were further analyzed using Ingenuity Pathway Analysis (IPA) for identification of key regulator genes. IPA recognized 20 key regulator genes of which five were differentially expressed in sensitive versus resistant cell lines. The mRNA level of these five genes was further assessed in a panel of 25 HNSCC cell lines using quantitative real-time PCR. Among these key regulators, MMP-7 and MMP-13 are implicated as potential biomarkers of ICS. Taken together, genome-wide transcriptional analysis identified single genes, GO categories as well as molecular networks that are differentially expressed in HNSCC cell lines with different ICS. Furthermore, two novel predictive biomarkers for cisplatin resistance, MMP-7 and MMP-13, were identified.

Background: Epidermal growth factor receptor (EGFR) is a target for treatment in tongue cancer. Here, EGFR ligands were evaluated for their potential uses as predictive biomarkers of cetuximab treatment response.

Methods: In three tongue cancer cell lines the influences of epidermal growth factor (EGF), amphiregulin (AR), and epiregulin (EPR) on tumour cell proliferation and cetuximab response were evaluated by the addition of recombinant human (rh) proteins or the siRNA-mediated downregulation of endogenous ligand production.

Results: EGF or AR downregulation suppressed the proliferation of all investigated cell lines. Furthermore, all cell lines displayed increased cetuximab resistance upon the addition of rhEGF, whereas EGF silencing resulted in an improved cetuximab response in one cell line.

Conclusions: Our data suggest that EGF and AR are critical components of the EGFR signalling network required for full proliferative potential. Moreover, EGF is a potential predictive biomarker of poor cetuximab response and a possible treatment target.

A growing body of evidence suggests that components of the tumor microenvironment, including cancer-associated fibroblasts (CAF), may modulate the treatment sensitivity of tumor cells. Here, we investigated the possible influence of CAFs on the sensitivity of head and neck squamous cell carcinoma (HNSCC) cell lines to cetuximab, an antagonistic epidermal growth factor receptor (EGFR) antibody. Cetuximab treatment caused a reduction in the proliferation rate of HNSCC cell lines, whereas the growth of HNSCC-derived CAF cultures was unaffected. When tumor cells were cocultured with CAFs in a transwell system, the cetuximab-induced growth inhibition was reduced, and a complete protection from growth inhibition was observed in one of the tumor cell lines investigated. Media that had been conditioned by CAFs offered protection from cetuximab treatment in a concentration-dependent manner, suggesting that the resistance to treatment was mediated by CAF-derived soluble factors. The coculture of HNSCC cell lines with CAFs resulted in an elevated expression of matrix metalloproteinase-1 (MMP-1) in both the tumor cells and CAFs. Moreover, the CAF-induced resistance was partly abolished by the presence of an MMP inhibitor. However, CAFs treated with siRNA targeting MMP-1 still protected tumor cells from cetuximab treatment, suggesting that several MMPs may cooperate to facilitate resistance or that the protective effect is mediated by another member of the MMP family. These results identify a novel CAF-dependent modulation of cetuximab sensitivity and suggest that inhibiting MMPs may improve the effects of EGFR-targeted therapy.

Cancer-associated fibroblasts (CAFs) are one of the main components of the tumor stroma and are known to increase tumor growth and stimulate  invasion and metastasis. Increasing evidence suggests that CAFs may also be an important determinant of the response to various treatments. In this study we aimed to characterize the molecular cross-talk between CAFs and head and neck squamous cell carcinoma (HNSCC) cells.

HNSCC cell lines were co-cultured with their patient-matched CAFs for seven days, after which the gene expression of tumor cells was investigated by Affymetrix microarray. 58 protein coding genes were found to be differentially expressed (Q≤0.05) in tumor cells cocultured with CAFs when compared to tumor cells cultured alone. The top functions of these genes were cancer, cellular movement, and embryonic development as analyzed by Ingenuity Pathway Analysis. Nine genes were upregulated by ≥1.5-fold while the expression of 35 genes was found to be reduced by ≤ 0.67-fold. Several of the differentially expressed genes have been associated with epithelial-to-mesenchymal transition (EMT). The change in the expression of POSTN, GREM1, COL1A2, VIM, and MMP7 was verified by qPCR analysis. Moreover, the influence of CAFs on the proliferation, migration and cetuximab sensitivity of tumor cells was investigated, and was found to vary among the tumor cell-CAF pairs.

In conclusion, we demonstrate that CAF-derived signals cause changes in the expression of multiple genes, several of which are associated with an EMT phenotype of tumor cells. Furthermore, CAFs modulate the proliferation, migration and cetuximab treatment response of tumor cells.