Tumors with non-functional RB1 are killed by reduced gamma-tubulin levels.

In various tumors inactivation of growth control is achieved by interfering with the RB1 signaling pathway. Here, we describe that RB1 and γ tubulin proteins moderate each other's expression by binding to their respective gene promoters. Simultaneous reduction of RB1 and γ tubulin protein levels result in an E2F1-dependent upregulation of apoptotic genes such as caspase 3. We report that in various tumors types, there is an inverse correlation between the expression levels of γ tubulin and RB1 and that in tumor cell lines with a non-functioning RB1, reduction of γ tubulin protein levels leads to induction of apoptosis. Thus, the RB1/γ tubulin signal network can be considered as a new target for cancer treatment.