Premalignancy and cellular senescence

Tumorigenesis is s a multistage process characterized by multiple genetic and molecular insults. The progression from premalignancy to malignancy requires bypass of tumor suppressor mechanisms such as apoptosis and cellular senescence. While apoptosis has long been considered a tumor suppressor mechanism, senescence has recently been verifi ed to be a major impediment for cancer progression, especially in premalignant lesions. In this chapter, we discuss the characteristics of premalignant in comparison to malignant tumors, the role of senescence in impeding the transition, and the mechanisms by which tumor cells are able to escape cellular senescence during cancer progression. This chapter also summarizes what is currently known about the process of cellular senescence in tumor suppression, including the inducers, markers, and molecular pathways involved. Finally, we discuss implications of induction of cellular senescence as a therapeutic strategy in clinical management of premalignant and malignant tumors.