The Bcl-2 protein contributes to both oncogenesis and intrinsic cancer treatment resistance by inhibiting apoptosis. Research supported by this grant is investigating one particular aspect of Bcl-2's mechanism of action, the inhibition of calcium signals that promote apoptosis. We discovered that Bcl-2 interacts with the inositol 1,4,5-trisphosphate receptor (IP3R), an IP3-gated calcium channel on the endoplasmic reticulum (ER), thus inhibiting IP3-induced calcium elevation. In the current funding period we used FRET to demonstrate this interaction in cells and mapped the interaction sites on both Bcl-2 and the IP3R. Based on this information we developed a peptide inhibitor of Bcl-2-IP3R interaction, Peptide 2. This peptide, when delivered into cells, reverses the inhibition of pro-apoptotic calcium signals by Bcl-2 and triggers prolonged calcium oscillations that elevate the pro-apoptotic protein Bim. The present proposal continues this work by investigating the fundamental mechanism by which Bcl-2-IP3R interaction regulates IP3R channel activity and thus inhibits IP3- dependent calcium elevation. Also, this proposal investigates the mechanism by which Peptide 2-mediated inhibition of Bcl-2-IP3R interaction triggers calcium oscillations and increases Bim levels. Finally, this proposal explores the concept of targeting Bcl-2-IP3R interaction for treatment of Bcl-2 over-expressing cancers, including chronic lymphocytic leukemia, in synergy with other therapeutic agents.
Bcl-2 is a very important protein that contributes to cancer. It functions to inhibit the death of cells. Therefore, when cancer cells have too much of this protein they fail to die. Thus, the cancer cells accumulate and are resistant to treatments designed to induce cell death. This proposal is for research to better understand how Bcl-2 inhibits cell death. The goal is to understand how Bcl-2 interacts with and regulates channels that conduct calcium ions within cancer cells. These ions are important in mediating cell death. Our research is investigating the hypothesis that Bcl-2 closes these channels and thus prevents the calcium ion from inducing cell death. By understanding this process we may be able to develop new treatments for cancer that overcome the cell death inhibiting function of Bcl-2.
|Lavik, Andrew R; Zhong, Fei; Chang, Ming-Jin et al. (2015) A synthetic peptide targeting the BH4 domain of Bcl-2 induces apoptosis in multiple myeloma and follicular lymphoma cells alone or in combination with agents targeting the BH3-binding pocket of Bcl-2. Oncotarget 6:27388-402|
|Rosko, Ashley E; McColl, Karen S; Zhong, Fei et al. (2014) Acidosis Sensing Receptor GPR65 Correlates with Anti-Apoptotic Bcl-2 Family Member Expression in CLL Cells: Potential Implications for the CLL Microenvironment. J Leuk (Los Angel) 2:|
|Chang, Ming-Jin; Zhong, Fei; Lavik, Andrew R et al. (2014) Feedback regulation mediated by Bcl-2 and DARPP-32 regulates inositol 1,4,5-trisphosphate receptor phosphorylation and promotes cell survival. Proc Natl Acad Sci U S A 111:1186-91|
|Greenberg, Edward F; Lavik, Andrew R; Distelhorst, Clark W (2014) Bcl-2 regulation of the inositol 1,4,5-trisphosphate receptor and calcium signaling in normal and malignant lymphocytes: potential new target for cancer treatment. Biochim Biophys Acta 1843:2205-10|
|Akl, H; Monaco, G; La Rovere, R et al. (2013) IP3R2 levels dictate the apoptotic sensitivity of diffuse large B-cell lymphoma cells to an IP3R-derived peptide targeting the BH4 domain of Bcl-2. Cell Death Dis 4:e632|
|Ryder, Christopher B; McColl, Karen; Distelhorst, Clark W (2013) Acidosis blocks CCAAT/enhancer-binding protein homologous protein (CHOP)- and c-Jun-mediated induction of p53-upregulated mediator of apoptosis (PUMA) during amino acid starvation. Biochem Biophys Res Commun 430:1283-8|
|Liu, Wei Michael; Huang, Ping; Kar, Niladri et al. (2013) Lyn facilitates glioblastoma cell survival under conditions of nutrient deprivation by promoting autophagy. PLoS One 8:e70804|
|Monaco, G; Decrock, E; Akl, H et al. (2012) Selective regulation of IP3-receptor-mediated Ca2+ signaling and apoptosis by the BH4 domain of Bcl-2 versus Bcl-Xl. Cell Death Differ 19:295-309|
|Ryder, Christopher; McColl, Karen; Zhong, Fei et al. (2012) Acidosis promotes Bcl-2 family-mediated evasion of apoptosis: involvement of acid-sensing G protein-coupled receptor Gpr65 signaling to Mek/Erk. J Biol Chem 287:27863-75|
|Distelhorst, Clark W; Bootman, Martin D (2011) Bcl-2 interaction with the inositol 1,4,5-trisphosphate receptor: role in Ca(2+) signaling and disease. Cell Calcium 50:234-41|
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