A new membrane marker for commitment of human bronchial epithelial cells to terminal squamous differentiation

Squamous differentiation in human bronchial epithelial (HBE) cells is a metaplastic change that occurs primarily after chronic injury and often precedes squamous cell carcinoma. After treating HBE cells with inducing agents for various periods followed by removal of these agents and assay for terminal squamous differentiation, HBE cells were found to become committed sqamous differentiation after 12-36 hours of treatment. Expression of a membrane marker, SQM1 protein, increased during the commitment stage, peaked shortly after commitment and gradually decreased in the later stages of squamous differentiation of HBE cells. The lack of marked morphological and biochemical changes associated with the commitment and early stages of squamous differentiation makes SQM1 protein a useful marker for the study of squamous differentiation and metaplasia of HBE cells.