Head and neck squamous cell carcinoma (HNSCC) is the sixth leading malignancy worldwide, with a poor prognosis and limited treatment options. Molecularly targeted therapies for HNSCC are still lacking. However, recent reports provide novel insights about many molecular alterations in HNSCC that may be useful in future therapies. Therefore, it is necessary to identify new biomarkers that may provide a better prediction of the disease and promising targets for personalized therapy. The poor response of HNSCC to therapy is attributed to a small population of tumor cells called cancer stem cells (CSCs). Growing evidence indicates that the Hedgehog (HH) signaling pathway plays a crucial role in the development and maintenance of head and neck tissues. The HH pathway is normally involved in embryogenesis, stem cell renewal, and tissue regeneration. However, abnormal activation of the HH pathway is also associated with carcinogenesis and CSC regulation. Overactivation of the HH pathway was observed in several tumors, including basal cell carcinoma, that are successfully treated with HH inhibitors. However, clinical studies about HH pathways in HNSCC are still rare. In this review, we summarize the current knowledge and recent advances regarding the HH pathway in HNSCC and discuss its possible implications for prognosis and future therapy.

Background/Aim: The biological behaviour of oral squamous cell carcinoma (OSCC) might be an effect of aberrant activation of several signalling pathways, like WNT and NOTCH pathways. The purpose of this study was to investigate the prognostic significance of WNT1 and NOTCH1 in patients with OSCC in relation to pro-angiogenic factors (PDGFRβ, CXCR4). Materials and Methods: Immunohistochemistry was performed in 60 OSCC tissue samples to compare WNT1, NOTCH1, PDGFRβ, and CXCR4 expression and correlate it with clinicopathological parameters. Results: Immunoreactivity of WNT1, NOTCH1, PDGFRβ, and CXCR4 was found in 51.7%, 25.0%, 63.3%, and 70.0% of the patients, respectively. WNT1 expression was positively correlated with NOTCH1 (r=0.269, p=0.037) and CXCR4 (r=0.268, p=0.038). Positive correlation was observed also between NOTCH1 and CXCR4 (r=0.493, p<0.001). WNT1 and PDGFRβ expression was significantly associated with shorter overall survival (p=0.042, p=0.033, respectively). Multivariate Cox regression model revealed that WNT1 and CXCR4 were independent prognostic factors (p=0.009, p=0.021, respectively). Conclusion: WNT1 and NOTCH1 expression is associated with CXCR4 expression in OSCC, suggesting that WNT and NOTCH pathways are important in oral tumour angiogenesis. Moreover, WNT1 and CXCR4 could serve as independent prognostic factors for patients with OSCC.

Oral lichen planus (OLP) is a chronic inflammatory disease. There are no markers that can be used to identify the risk of a malignant transformation of OLP to oral squamous cell carcinoma (OSCC). Immunohistochemical staining was performed among 56 patients with OLP and 66 patients with OSCC for p53, HSP90 and E-cadherin expression and presence of HPV16/18. Significant differences in p53 and HSP90 expression between OLP and OSCC were found (p = 0.01 and p = 0.006, respectively). A positive correlation between HSP90 and p53 expression was seen in OLP (p = 0.017). Univariate analysis identified HSP90 expression and HPV16/18 presence as prognostic factors for overall survival time (OS) (p < 0.05). In multivariate analysis, only HSP90 expression was an independent prediction factor for shorter OS of OSCC patients (p = 0.016). The present study suggests that cooperation between p53 and HSP90 as well as between HPV16/18 and HSP90 exists in OLP and may affect the biological behaviour of OLP. The observed expression of HSP90 and p53 in OLP and their increase in OSCC suggests that these proteins participate in the malignant transformation of OLP. HSP90 may be a potential independent prognostic biomarker that can predict poor prognosis in OSCC.

Sonic Hedgehog is a novel prognostic biomarker in patients with oral squamous cell carcinoma

Background/Aim: Oral squamous cell carcinoma (OSCC) is a highly invasive malignancy with poor prognosis. Recent reports suggest that Sonic Hedgehog (SHH) plays a key role in tumor progression and worsens the response to therapy, possibly through an association with a cancer stem cell (CSC) phenotype. The objective of our study was to investigate the relationship between SHH expression and CSC markers in OSCC. Materials and Methods: A total of 67 OSCC specimens were immunostained for SHH and CSC markers using specific antibodies and expression was correlated with clinicopathological parameters. Results: SHH expression was significantly correlated with CD133 (p=0.026, r=0.272) and SRY-box transcription factor 2 (SOX2; p<0.001, r=0.793). SHH and SOX2 expression were associated with worse survival in OSCC (p=0.003 and p=0.003, respectively). In multivariate analysis SHH and CD44 were independent prognostic biomarkers in patients with OSCC (p=0.001 and p=0.008, respectively). Conclusion: Our study revealed that SHH overexpression is closely associated with CSC markers, contributing to tumor progression and worse outcomes of patients with OSCC.