Inactivation of the retinoblastoma tumor suppressor protein, Rb, is essential for the progression of cell cycle from G1 to the S phase. Rb gene or its gene product is inactivated in a wide variety of cancers, either by mutation of the gene or functional inactivation of the protein. During normal cell cycle progression, Rb is inactivated by a cascade of phosphorylation events, mediated by kinases associated with the D and E type cyclins. Studies from our lab have shown that growth factor stimulation of quiescent cells leads to the binding of a cellular signaling kinase, Raf-1, to the Rb proteins. This binding of Raf-1 to Rb precedes the binding of cyclins and cdks and appears to be essential for the subsequent phosphorylation of Rb. Disruption of the binding of Raf-1 to Rb using a peptide inhibitor prevented Rb phosphorylation, cell cycle progression, angiogenesis as well as tumor growth in nude mice. Based on these findings, we propose to identify and develop small molecules that can disrupt the Rb-Raf-1 interaction. Such compounds can be expected to have anti-proliferative as well as anti-neoplastic activities and might be of use as anti-cancer agents. Indeed, our preliminary screen of a drug library led tot he identification of two small molecules capable of disrupting the binding of Raf-1 to Rb selectively and with reasonable potency. They were effective in arresting cell proliferation and one of the compounds could inhibit or retard tumor growth in nude mice. Based on these results, we propose to carry out the following studies: (1) To identify and synthesize small molecules to disrupt Rb-Raf-1 interaction (2) To assess the specificity and efficacy of the Rb-Raf-1 inhibitors in vitro (3) To evaluate the effects of Rb-Raf-1 disrupters on cell proliferation and angiogenesis. (4) To evaluate the effect of Rb-Raf-1 disrupters on tumor growth and metastasis in vivo. Dr. Nick Lawrence's laboratory w ill synthesize combinatorial drug libraries based on initial hits from the drug screen. Additional screening of larger libraries will also be done to identify more potent inhibitors than the ones already identified. These compounds will be subjected to extensive in vitro and in vivo analysis for their efficacy as anti-tumor drugs. Further, these compounds will be used to study the biological events taking place in the cell during early stages of cell cycle. These compounds will also be used extensively to study other signaling pathways examined in the sister projects of this PO-1 application.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Program Projects (P01)
Project #
Application #
Study Section
Special Emphasis Panel (ZCA1)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
H. Lee Moffitt Cancer Center & Research Institute
United States
Zip Code
Kazi, Aslamuzzaman; Ozcan, Sevil; Tecleab, Awet et al. (2014) Discovery of PI-1840, a novel noncovalent and rapidly reversible proteasome inhibitor with anti-tumor activity. J Biol Chem 289:11906-15
Ozcan, Sevil; Kazi, Aslamuzzaman; Marsilio, Frank et al. (2013) Oxadiazole-isopropylamides as potent and noncovalent proteasome inhibitors. J Med Chem 56:3783-805
Treviño, José G; Verma, Monika; Singh, Sandeep et al. (2013) Selective disruption of rb-raf-1 kinase interaction inhibits pancreatic adenocarcinoma growth irrespective of gemcitabine sensitivity. Mol Cancer Ther 12:2722-34
Ge, Yiyu; Kazi, Aslamuzzaman; Marsilio, Frank et al. (2012) Discovery and synthesis of hydronaphthoquinones as novel proteasome inhibitors. J Med Chem 55:1978-98
Davis, Rebecca; Pillai, Smitha; Lawrence, Nicholas et al. (2012) TNF-?-mediated proliferation of vascular smooth muscle cells involves Raf-1-mediated inactivation of Rb and transcription of E2F1-regulated genes. Cell Cycle 11:109-18
Kim, Young B; Balasis, Maria E; Doi, Kenichiro et al. (2012) Synthesis and evaluation of substituted hexahydronaphthalenes as novel inhibitors of the Mcl-1/BimBH3 interaction. Bioorg Med Chem Lett 22:5961-5
Johnson, Jackie L; Pillai, Smitha; Pernazza, Danielle et al. (2012) Regulation of matrix metalloproteinase genes by E2F transcription factors: Rb-Raf-1 interaction as a novel target for metastatic disease. Cancer Res 72:516-26
Doi, Kenichiro; Li, Rongshi; Sung, Shen-Shu et al. (2012) Discovery of marinopyrrole A (maritoclax) as a selective Mcl-1 antagonist that overcomes ABT-737 resistance by binding to and targeting Mcl-1 for proteasomal degradation. J Biol Chem 287:10224-35
Li, X; Gilkes, D; Li, B et al. (2012) Abnormal MDMX degradation in tumor cells due to ARF deficiency. Oncogene 31:3721-32
Win-Piazza, Hla; Schneeberger, Valentina E; Chen, Liwei et al. (2012) Enhanced anti-melanoma efficacy of interferon alfa-2b via inhibition of Shp2. Cancer Lett 320:81-5

Showing the most recent 10 out of 39 publications