A novel small-molecule inhibitor of protein kinase D blocks pancreatic cancer growth in vitro and in vivo.

Abstract

Protein kinase D (PKD) family members are increasingly implicated in multiple normal and abnormal biological functions, including signaling pathways that promote mitogenesis in pancreatic cancer. However, nothing is known about the effects of targeting PKD in pancreatic cancer. Our PKD inhibitor discovery program identified CRT0066101 as a specific inhibitor of all PKD isoforms. The aim of our study was to determine the effects of CRT0066101 in pancreatic cancer. Initially, we showed that autophosphorylated PKD1 and PKD2 (activated PKD1/2) are significantly upregulated in pancreatic cancer and that PKD1/2 are expressed in multiple pancreatic cancer cell lines. Using Panc-1 as a model system, we showed that CRT0066101 reduced bromodeoxyuridine incorporation; increased apoptosis; blocked neurotensin-induced PKD1/2 activation; reduced neurotensin-induced, PKD-mediated Hsp27 phosphorylation; attenuated PKD1-mediated NF-kappaB activation; and abrogated the expression of NF-kappaB-dependent proliferative and prosurvival proteins. We showed that CRT0066101 given orally (80 mg/kg/d) for 24 days significantly abrogated pancreatic cancer growth in Panc-1 subcutaneous xenograft model. Activated PKD1/2 expression in the treated tumor explants was significantly inhibited with peak tumor concentration (12 micromol/L) of CRT0066101 achieved within 2 hours after oral administration. Further, we showed that CRT0066101 given orally (80 mg/kg/d) for 21 days in Panc-1 orthotopic model potently blocked tumor growth in vivo. CRT0066101 significantly reduced Ki-67-positive proliferation index (P < 0.01), increased terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive apoptotic cells (P < 0.05), and abrogated the expression of NF-kappaB-dependent proteins including cyclin D1, survivin, and cIAP-1. Our results show for the first time that a PKD-specific small-molecule inhibitor CRT0066101 blocks pancreatic cancer growth in vivo and show that PKD is a novel therapeutic target in pancreatic cancer.

• Authors: Kuzhuvelil B Harikumar, Ajaikumar B Kunnumakkara, Nobuo Ochi, Zhimin Tong, Amit Deorukhkar, Bokyung Sung, Lloyd Kelland, Stephen Jamieson, Rachel Sutherland, Tony Raynham, Mark Charles, Azadeh Bagherzadeh, Azadeh Bagherazadeh, Caroline Foxton, Alexandra Boakes, Muddasar Farooq, Dipen Maru, Parmeswaran Diagaradjane, Yoichi Matsuo, James Sinnett-Smith, Juri Gelovani, Sunil Krishnan, Bharat B Aggarwal, Enrique Rozengurt, Christopher R Ireson, Sushovan Guha
• Journal: Molecular cancer therapeutics (Mol Cancer Ther) Vol. 9 Issue 5 Pg. 1136-46 (May 2010) ISSN: 1538-8514 [Electronic] United States
• PMID: 20442301 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Antineoplastic Agents
• CRT 0066101
• Protein Kinase Inhibitors
• Pyrimidines
• protein kinase D
• Protein Kinase C

Topics

• Administration, Oral
• Animals
• Antineoplastic Agents (administration & dosage, chemistry, pharmacology, therapeutic use)
• Apoptosis (drug effects)
• Carcinoma, Pancreatic Ductal (drug therapy, pathology)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Humans
• Male
• Mice
• Mice, Nude
• Molecular Weight
• Pancreatic Neoplasms (drug therapy, pathology)
• Protein Kinase C (antagonists & inhibitors)
• Protein Kinase Inhibitors (administration & dosage, chemistry, pharmacology, therapeutic use)
• Pyrimidines (pharmacology, therapeutic use)
• Xenograft Model Antitumor Assays