Late stage prostate cancer (CAP) tumors are resistant to anticancer therapies that cause cell death through the induction of apoptosis. To understand how CaP cells become resistant to apoptotic stimuli, it is important to characterize the molecular pathways that control apoptosis. This proposal focuses on the requirement of the transcription factor NF-KB for cell survival in CaP cells in response to interleukin-1 (IL-1)13-dependent Ca R+signaling and apoptosis. Preliminary data presented in this proposal demonstrates that IL-113-induced NF-_zB activity will overcome _rowth factor induced apoptosis in CaP cells. However, IL-113 will also induce apoptosis in CaP cells through a Ca2_-dependent pathway, following the inactivation of NF-_:B. These results suggest that NF-KB activity is required to maintain Ca 2+ homeostasis in CaP cells following IL-lJ3 stimulation. This is supported by the fact that IL-lJ3 activates NF-KB, in part, through Ca2+/calmodulin-dependent kinases (CaMKs), namely CaMKK and CaMKIV. IL-l[3-induced NF-KB activity is required to upregulate transcripts encoding CaZ+-binding proteins (CaBP), including calreticulin, calbindin-3, and DSCR1. Expression of calreticulin blocked Ca _ -induced apoptosis in our model system. The overall hypothesis of this proposal is that IL-1 [3-induced NF-KB activity is required to upregulate gene products that feedback to regulate Ca 2+ levels and modulate apoptosis in CaP cells. To address this hypothesis, the following aims will be explored.
Aim 1 will establish whether CaP patients,2+,display, elevated IL-113. Experiments' proposed in Aim 1 will also identify whether intracellular release of Ca is responsible for inducing apoptosis, and will determine if this effect impacts cytochrome c release, caspase and/or calpain activation, and subsequent cleavage of CaMK and IKB/NF-KB substrates.
Aim 2 will identify the CaMK signaling pathways responsible for upregulating NF-KB transcriptional activity and cell survival. Experiments outlined in Aim 2 will use dominant negative and constitutively active kinases to identify CaMK pathways required to activate NF-_cB in response to IL-I[3, and will determine the impact of these signaling pathways on the transactivation potential of NF-KB.
Aim 3 will elucidate whether the calreticulin promoter is a direct target of NF-KB and determine if the expression of calreticulin alone or in combination with other NF-KB-regulated CaBPs rescues apoptosis. Experiments described in Aim 3 will determine v_hether NF-KB directly upregulates the calreticulin promoter, and will potentially identify other NF-?B regulated Ca,2+ -bin- din-g proteins. Additional experiments proposed in Aim 3 will determine whether the expression of these proteins alone or in combination with calreticulin will rescue Ca2+. inducedapopto_} Collectively, the experiments outlined in this proposal will offer insight into the anti-apoptotic role of NF-_cBin Ca z signaling in CaP cells, and will potentially provide a better understanding of how NF-KB overcomes Ca2+-induced apoptotic cues initiatcd by growth factors and cytokines.
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