Oral squamous cell carcinoma (OSCC), derived from normal oral epithelium transformation, remains a major public health problem world-wide. The prognosis of OSCCs that occur on lips is good, while other sites of oral mucosa where OSCC appears are more progressive, invasive and metastatic. A small subset of cells within a malignant neoplasm, named cancer stem cells (CSCs) or tumour initiating cells are thought to be capable of initiating the neoplasm itself, and of driving its growth and recurrance after treatment. The precise origin of CSCs is an ambiguous issue at present. The first proposal of the origin of CSCs is that CSCs develop from tumour cells themselves via cellular dedifferentiation. The secondary hypothesis for the origin of CSCs proposes that CSCs are the product of malignant transformation of adult stem cells. In this Ph.D thesis, we tried to demonstrate that CSCs in OSCC may be produced from those pathways.