Geranylgeranyltransferase I inhibitors target RalB to inhibit anchorage-dependent growth and induce apoptosis and RalA to inhibit anchorage-independent growth.

Falsetti, S; Wang, D; Peng, H; Carrico, D; Cox, A; Der, C; Hamilton, A; Sebti, S

Journal article

Geranylgeranyltransferase I inhibitors target RalB to inhibit anchorage-dependent growth and induce apoptosis and RalA to inhibit anchorage-independent growth.

Abstract:: Geranylgeranyltransferase I inhibitors (GGTIs) are presently undergoing advanced preclinical studies and have been shown to disrupt oncogenic and tumor survival pathways, to inhibit anchorage-dependent and -independent growth, and to induce apoptosis. However, the geranylgeranylated proteins that are targeted by GGTIs to induce these effects are not known. Here we provide evidence that the Ras-like small GTPases RalA and RalB are exclusively geranylgeranylated and that inhibition of their geranylgeranylation mediates, at least in part, the effects of GGTIs on anchorage-dependent and -independent growth and tumor apoptosis. To this end, we have created the corresponding carboxyl-terminal mutants that are exclusively farnesylated and verified that they retain the subcellular localization and signaling activities of the wild-type geranylgeranylated proteins and that Ral GTPases do not undergo alternative prenylation in response to GGTI treatment. By expressing farnesylated, GGTI-resistant RalA and RalB in Cos7 cells and human pancreatic MiaPaCa2 cancer cells followed by GGTI-2417 treatment, we demonstrated that farnesylated RalB, but not RalA, confers resistance to the proapoptotic and anti-anchorage-dependent growth effects of GGTI-2417. Conversely, farnesylated RalA but not RalB expression renders MiaPaCa2 cells less sensitive to inhibition of anchorage-independent growth. Furthermore, farnesylated RalB, but not RalA, inhibits the ability of GGTI-2417 to suppress survivin and induce p27(Kip1) protein levels. We conclude that RalA and RalB are important, functionally distinct targets for GGTI-mediated tumor apoptosis and growth inhibition.

Publication status:: Published

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APA Style

Falsetti, S., Wang, D., Peng, H., Carrico, D., Cox, A., Der, C., Hamilton, A., & Sebti, S. (2007). Geranylgeranyltransferase I inhibitors target RalB to inhibit anchorage-dependent growth and induce apoptosis and RalA to inhibit anchorage-independent growth. Molecular and Cellular Biology, 27(22), 8003–8014.

MLA Style

Falsetti, S, et al. “Geranylgeranyltransferase I Inhibitors Target RalB to Inhibit Anchorage-Dependent Growth and Induce Apoptosis and RalA to Inhibit Anchorage-Independent Growth.” Molecular and Cellular Biology, vol. 27, no. 22, 2007, pp. 8003–14.

Chicago Style

Falsetti, S, D Wang, H Peng, et al. 2007. “Geranylgeranyltransferase I Inhibitors Target RalB to Inhibit Anchorage-Dependent Growth and Induce Apoptosis and RalA to Inhibit Anchorage-Independent Growth.” Molecular and Cellular Biology 27 (22): 8003–14.
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