[摘要]：Although senescence in oncogenesis has been widely studied, little is known regarding the role of this process in chemotherapy resistance. Thus, from the standpoint of enhancing and improving cancer therapy, a better understanding of the molecular machinery involved in chemotherapy-related senescence is paramount. We show for the first time that Mcl-1, a Bcl-2 family member, plays an important role in preventing chemotherapy-induced senescence (CIS). Overexpression of Mcl-1 in p53(+) cell lines inhibits CIS. Conversely, downregulation of Mcl-1 makes cells sensitive to CIS. Surprisingly, downregulation of Mcl-1 in p53(-) cells restored CIS to similar levels as p53(+) cells. In all cases where senescence can be induced, we observed increased p21 expression. Moreover, we show that the domain of Mcl-1 responsible for its antisenescent effects is distinct from that known to confer its antiapoptotic qualities. In vivo we observe that downregulation of Mcl-1 can almost retard tumor growth regardless of p53 status, while overexpression of Mcl-1 in p53(+) cells conferred resistance to CIS and promoted tumor outgrowth. In summary, our data reveal that Mcl-1 can inhibit CIS in both a p53-dependent and -independent manner in vitro and in vivo and that this Mcl-1-mediated inhibition can enhance tumor growth in vivo.
