Squamous cell carcinoma is one of the most common malignancies in head and neck region. Primary tumors, especially derived from undifferentiated cells, tend to have aggressive phenotypes, which are mainly characterized by local recurrence and distant metastasis. In this study we found that Id-1, a negative regulator of tissue specific transcription factors, is highly expressed in head and neck squamous carcinoma cells (HNSCC), and that the expression is correlated with the malignant phenotype, i.e., cell proliferation and invasion. Id-1 knockdown dramatically reduces squamous cell invasion that is accompanied by profound morphologic changes and robust reduction in expression levels of mesenchymal markers.In addition, reduction in tumor growth and neoangiogenesis were observed in vivo, indicating that knock-down of Id-1 drastically suppresses VEGFA expression. Our results also suggested that VEGFA-autocrine loop activates tylosine kinase pathways including Srk and FAK, and therefore manifests invasive phenotype. With clinical materials obtained from HNSCC patients, significant correlation was observed between Id-1 and VEGFA. Furthermore, we demonstrated that a non toxic compound, cannabidiol, significantly downregulates Id-1 gene expression and associated squamous cell proliferation and invasiveness. Taken together, these results suggest that Id-1 controls cancer cell phenotype in culture and in vivo, and that drugs targeting Id-1 represent a novel and promising strategy for improving the therapy and outcome of patients with HNSCC.

Citation Format: Ryuichi Murase, Sean McAllister, Yohei Fujita, Tomoki Sumida, Koichi Nakashiro, Pierre Desprez, Hiroyuki Hamakawa. Id-1 gene and protein as therapeutic target for head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1017. doi:10.1158/1538-7445.AM2014-1017