ABSTRACT
NF-κB essential modulator (NEMO) binds and regulates IκB kinase (IKK) and is required for NF-κB activation. The NEMO-binding domain peptide (NBDP) of IKK was found to inhibit NF-κB activation and promote apoptosis in cancer cells. Studies have shown that constitutive NF-κB activation, one of the signature molecular alterations in pancreatic ductal adenocarcinoma (PDAC), is a potential therapeutic target. However, preclinical and therapeutic evidence that supports direct targeting of IKK activation in therapy is lacking. The aim of this study was to determine whether the combination of NBDP and gemcitabine would sensitize pancreatic cancer to the gemcitabine. We confirmed that NBDP inhibited NF-κB activation and found that NBDP indeed promoted chemo-sensitivity to gemcitabine in PDAC. NBDP increased PARP and caspase 3 cleavage in the apoptosis pathway, increased apoptosis of PDAC cells, and suppressed PDAC cell growth in vitro. In addition, NBDP combined with gemcitabine significantly decreased levels of NF-κB activity and inhibited the growth of PDAC in vivo in an orthotopic xenograft mouse model. Mechanistic investigations showed that NBDP effectively competed with NEMO/IKKγ for binding to IKKs and thus inhibited IKK and NF-κB activation, down-regulated expression levels of Erk, and decreased PDAC cell growth. Taken together, our current data demonstrate that NBDP sensitizes human pancreatic cancer to gemcitabine by inhibiting the NF-κB pathway. NBDP is a potential adjuvant chemotherapeutic agent for treating pancreatic cancer.
Subject(s)
Carcinoma, Pancreatic Ductal/drug therapy , I-kappa B Kinase/pharmacology , NF-kappa B/antagonists & inhibitors , Pancreatic Neoplasms/drug therapy , Peptide Fragments/pharmacology , Animals , Antineoplastic Combined Chemotherapy Protocols/pharmacology , Carcinoma, Pancreatic Ductal/metabolism , Carcinoma, Pancreatic Ductal/pathology , Cell Line, Tumor , Deoxycytidine/administration & dosage , Deoxycytidine/analogs & derivatives , Deoxycytidine/pharmacology , Drug Synergism , Female , Humans , I-kappa B Kinase/administration & dosage , I-kappa B Kinase/metabolism , Mice , Mice, Nude , NF-kappa B/metabolism , Pancreatic Neoplasms/metabolism , Pancreatic Neoplasms/pathology , Peptide Fragments/administration & dosage , Peptides/administration & dosage , Peptides/pharmacology , Protein Domains , Random Allocation , Xenograft Model Antitumor Assays , GemcitabineABSTRACT
The activation of nuclear factor κB (NF-κB) contributes to muscle degeneration that results from dystrophin deficiency in human Duchenne muscular dystrophy (DMD) and in the mdx mouse. In dystrophic muscle, NF-κB participates in inflammation and failure of muscle regeneration. Peptides containing the NF-κB Essential Modulator (NEMO) binding domain (NBD) disrupt the IκB kinase complex, thus blocking NF-κB activation. The NBD peptide, which is linked to a protein transduction domain to achieve in vivo peptide delivery to muscle tissue, was systemically delivered to mdx mice for 4 or 7 weeks to study NF-κB activation, histological changes in hind limb and diaphragm muscle and ex vivo function of diaphragm muscle. Decreased NF-κB activation, decreased necrosis and increased regeneration were observed in hind limb and diaphragm muscle in mdx mice treated systemically with NBD peptide, as compared to control mdx mice. NBD peptide treatment resulted in improved generation of specific force and greater resistance to lengthening activations in diaphragm muscle ex vivo. Together these data support the potential of NBD peptides for the treatment of DMD by modulating dystrophic pathways in muscle that are downstream of dystrophin deficiency.
