An integrated approach identifies mediators of local recurrence in head and neck squamous cell carcinoma

Head and Neck Squamous Cell Carcinoma (HNSCC) represents the sixth most common cancer worldwide, with about 550,000 new cases/year. Despite the development of precise and accurate surgery followed by radio- and/or chemo-therapy, in the last decade patients’ overall survival was only slightly improved. In particular, only 40-50% of patients with advanced HNSCC will survive for 5 years. The main worse prognostic event is considered the onset of loco-regional and distant recurrences, that is also accepted as surrogate markers of patients’ overall survival. HNSCC is a heterogeneous disease and, although many studies have been conducted to clarify the molecular mechanisms behind the development of local or distant metastasis, no clear molecular mediators of recurrence formation have been identified and no valid biomarkers exist to identify and treat patients at high-risk of recurrence. We aimed to fill this gap taking advantage of an unbiased approach in which we evaluated microRNA (miRNA) expression profile in a cohort of HNSCC primary tumours from recurrent and non-recurrent patients. We identified and validated a four-miRNA signature, composed by miR-1, miR-9, miR-133a and miR-150 that could be used as biomarker of recurrence. All these miRNAs are not only well-known molecular modulators of cell plasticity in different tumours, but intriguingly in our HNSCC model they are also able to classify HNSCC patients at high- or low-risk of recurrence formation. We demonstrated that these miRNAs collectively impinge on the epithelial-mesenchymal transition process. In silico and wet lab approaches showed that miR-9, expressed at high levels in recurrent HNSCC, targets the epithelial genes SASH1 and KRT13, while miR-1, miR-133a and miR-150, expressed at low levels in recurrent HNSCC, collectively target SP1 and TGF pathways. In vivo, a six-genes signature comprising the above targets, consistently predicts low progression free- and overall-survival in different panels of HNSCC samples. This is of particular clinical relevance, since the detection of this gene signature in tumours specimens could identify patients with poor prognosis who may benefit for a more accurate targeted therapy. In a preclinical model of HNSCC recurrence, the combined pharmacological inhibition of SP1 and TGF pathways, when timely administered, induced HNSCC cell death and prevented recurrence formation. By integrating different experimental approaches, we identified critical mediators of recurrence formation in advanced HNSCC. Since both SP1 and TGF pathways could be pharmacologically targeted, their combined inhibition may merit to be considered for future clinical development.