Fig. 2

Dual role of autophagy in tumorigenesis. Tumorigenesis begins with an oncogene mutation in the epithelial cell that makes the cell more likely to divide. The genetically altered or abnormal cells and its descendants grow and divide uncontrolled and rapidly at Hyperplasia stage. At Dysplasia stage, the overgrowing cells change their original form and behavior, have increased growth potential, and consist of more immature cells than mature. In situ cancer, the cells grow rapidly, but do not go into the process of maturation, have lost their tissue identity, and grow without regulation. In the malignant tumor (invasive cancer), the overgrowing cells invade neighboring areas and blood circulation systems from the primary tumor site by rupturing basal membrane. Metastases occur when cancer cells reach to the distant parts through lymphatic system and blood circulation. Autophagy plays dual roles during tumorigenesis including tumor-suppressing role during the early stage and cancer promoting role during the late stage