S Jagadeeshan1, A Subramanian2, S Tentu2, S Beesetti2, M Singhal2, S Raghavan2, R P Surabhi3, J Mavuluri2, H Bhoopalan3, J Biswal4, R S Pitani5, S Chidambaram5, S Sundaram6, R Malathi7, J Jeyaraman4, A S Nair8, G Venkatraman3, S K Rayala9. 1. Department of Biotechnology, Indian Institute of Technology Madras (IITM), Chennai Department of Genetics, University of Madras, Chennai. 2. Department of Biotechnology, Indian Institute of Technology Madras (IITM), Chennai. 3. Department of Human Genetics. 4. Department of Bioinformatics, Alagappa University, Karaikudi. 5. Department of CEFT. 6. Department of Pathology, Sri Ramachandra University, Porur, Chennai. 7. Department of Genetics, University of Madras, Chennai. 8. Rajiv Gandhi Centre for Biotechnology (RGCB), Thiruvananthapuram, Kerala, India. 9. Department of Biotechnology, Indian Institute of Technology Madras (IITM), Chennai rayala@iitm.ac.in.
Abstract
BACKGROUND: Therapeutic resistance to gemcitabine in pancreatic ductal adenocarcinoma (PDAC) is attributed to various cellular mechanisms and signaling molecules that influence as a single factor or in combination. DESIGN: In this study, utilizing in vitro p21-activated kinase 1 (Pak1) overexpression and knockdown cell line models along with in vivo athymic mouse tumor xenograft models and clinical samples, we demonstrate that Pak1 is a crucial signaling kinase in gemcitabine resistance. RESULTS: Pak1 kindles resistance via modulation of epithelial-mesenchymal transition and activation of pancreatic stellate cells. Our results from gemcitabine-resistant and -sensitive cell line models showed that elevated Pak1 kinase activity is required to confer gemcitabine resistance. This was substantiated by elevated levels of phosphorylated Pak1 and ribonucleotide reductase M1 levels in the majority of human PDAC tumors when compared with normal. Delineation of the signaling pathway revealed that Pak1 confers resistance to gemcitabine by preventing DNA damage, inhibiting apoptosis and regulating survival signals via NF-κB. Furthermore, we found that Pak1 is an upstream interacting substrate of transforming growth factor β-activated kinase 1-a molecule implicated in gemcitabine resistance. Molecular mechanistic studies revealed that gemcitabine docks with the active site of Pak1; furthermore, gemcitabine treatment induces Pak1 kinase activity both in vivo and in cell-free system. Finally, results from athymic mouse tumor models illustrated that Pak1 inhibition by IPA-3 enhances the cytotoxicity of gemcitabine and brings about pancreatic tumor regression. CONCLUSION: To our knowledge, this is the first study illustrating the mechanistic role of Pak1 in causing gemcitabine resistance via multiple signaling crosstalks, and hence Pak1-specific inhibitors will prove to be a better adjuvant with existing chemotherapy modality for PDAC.
BACKGROUND: Therapeutic resistance to gemcitabine in pancreatic ductal adenocarcinoma (PDAC) is attributed to various cellular mechanisms and signaling molecules that influence as a single factor or in combination. DESIGN: In this study, utilizing in vitro p21-activated kinase 1 (Pak1) overexpression and knockdown cell line models along with in vivo athymic mousetumor xenograft models and clinical samples, we demonstrate that Pak1 is a crucial signaling kinase in gemcitabine resistance. RESULTS:Pak1 kindles resistance via modulation of epithelial-mesenchymal transition and activation of pancreatic stellate cells. Our results from gemcitabine-resistant and -sensitive cell line models showed that elevated Pak1 kinase activity is required to confer gemcitabine resistance. This was substantiated by elevated levels of phosphorylated Pak1 and ribonucleotide reductase M1 levels in the majority of human PDAC tumors when compared with normal. Delineation of the signaling pathway revealed that Pak1 confers resistance to gemcitabine by preventing DNA damage, inhibiting apoptosis and regulating survival signals via NF-κB. Furthermore, we found that Pak1 is an upstream interacting substrate of transforming growth factor β-activated kinase 1-a molecule implicated in gemcitabine resistance. Molecular mechanistic studies revealed that gemcitabine docks with the active site of Pak1; furthermore, gemcitabine treatment induces Pak1 kinase activity both in vivo and in cell-free system. Finally, results from athymic mousetumor models illustrated that Pak1 inhibition by IPA-3 enhances the cytotoxicity of gemcitabine and brings about pancreatic tumor regression. CONCLUSION: To our knowledge, this is the first study illustrating the mechanistic role of Pak1 in causing gemcitabine resistance via multiple signaling crosstalks, and hence Pak1-specific inhibitors will prove to be a better adjuvant with existing chemotherapy modality for PDAC.
Authors: Nhi Huynh; Kai Wang; Mildred Yim; Chelsea J Dumesny; Mauro S Sandrin; Graham S Baldwin; Mehrdad Nikfarjam; Hong He Journal: BMC Cancer Date: 2017-06-19 Impact factor: 4.430
Authors: Chiara Marchetti; Katherine G Zyner; Stephan A Ohnmacht; Mathew Robson; Shozeb M Haider; Jennifer P Morton; Giovanni Marsico; Tam Vo; Sarah Laughlin-Toth; Ahmed A Ahmed; Gloria Di Vita; Ingrida Pazitna; Mekala Gunaratnam; Rachael J Besser; Ana C G Andrade; Seckou Diocou; Jeremy A Pike; David Tannahill; R Barbara Pedley; T R Jeffry Evans; W David Wilson; Shankar Balasubramanian; Stephen Neidle Journal: J Med Chem Date: 2018-02-07 Impact factor: 7.446