Abstract 3737: A novel mechanism of NF-κB activation by genotoxic chemotherapy

Abstract

Abstract CARP-1, a perinuclear phospho-protein, is a biphasic regulator of cell survival and apoptosis signaling. Genotoxic drugs induce apoptosis in part by elevating CARP-1 levels while also promote cell survival in part by activating NF-κB that involves CARP-1 interaction with NF-κB kinase subunit γ (aka, NEMO). We previously noted interaction of CARP-1 with RIPK1, and since RIPK1 is known to regulate NF-κB signaling, we investigated whether RIPK1-CARP-1 interaction is involved in genotoxic chemotherapy-dependent apoptosis or NF-κB-activated survival signaling. Mutagenesis and co-IP-WB analyses revealed that a 40-amino acid epitope within the amino-terminal catalytic domain of RIPK1 interacted with CARP-1 (611-640) peptide. Overexpression of this CARP-1/CCAR1-binding (CB) epitope peptide or RIPK1 mutant that has in-frame deletion of CB-epitope resulted in moderate but significant reduction in viabilities of cells treated with Adriamycin or Cisplatin relative to the viability loss noted in cells expressing RIPK1 (WT). However, no significant differences in loss of cell viabilities were noted in cells expressing various substitution mutants of RIPK1 (aspartate (D) 138 to asparagine (N), serine (S) 109 and threonine (T) 110 to alanines (A), lysine (K) 87 to arginine (R), K97 to R, K105 to R, or K115 to R) relative to their RIPK1 (WT) expressing counterparts when treated with genotoxic drugs. Interestingly, CB-epitope mutant, but not RIPK1 (WT), failed to translocate to cytoplasm in Adriamycin-treated cells. Genotoxic drugs activated p65/RelA in cells expressing RIPK1 (WT), while expression of RIPK1 CB-epitope mutant resulted in abrogation of p65/RelA activation by Adriamycin or Cisplatin but not by TNFα. Collectively our data demonstrate that CARP-1 interaction with RIPK1 promotes nuclear export of RIPK1 and consequent NF-κB activation in cells exposed to genotoxic drugs. Citation Format: Jaganathan Venkatesh, Magesh Muthu, Arun K. Rishi. A novel mechanism of NF-κB activation by genotoxic chemotherapy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3737.