Abrus agglutinin suppresses human hepatocellular carcinoma in vitro and in vivo by inducing caspase-mediated cell death
Abstract
Subhadip MUKHOPADHYAY1, Prashanta Kumar PANDA1, Durgesh Nandini DAS1, Niharika SINHA1, Birendra BEHERA2, Tapas Kumar MAITI2, Sujit Kumar BHUTIA1, *
1Department of Life Science, National Institute of Technology, Rourkela, Odisha, India; 2Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal, India
Aim: Abrus agglutinin (AGG) from the seeds of Indian medicinal plant Abrus precatorius belongs to the class II ribosome inactivating protein family. In this study we investigated the anticancer effects of AGG against human hepatocellular carcinoma in vitro and in vivo.
Methods: Cell proliferation, DNA fragmentation, Annexin V binding, immunocytofluorescence, Western blotting, caspase activity assays and luciferase assays were performed to evaluate AGG in human liver cancer cells HepG2. Immunohistochemical staining and TUNEL expression were studied in tumor samples of HepG2-xenografted nude mice.
Results: AGG induced apoptosis in HepG2 cells in a dose- and time-dependent manner. AGG-treated HepG2 cells demonstrated an increase in caspase 3/7, 8 and 9 activities and a sharp decrease in the Bcl-2/Bax ratio, indicating activation of a caspase cascade. Co-treatment of HepG2 cells with AGG and a caspase inhibitor or treatment of AGG in Bax knockout HepG2 cells decreased the caspase 3/7 activity in comparison to HepG2 cells exposed only to AGG. Moreover, AGG decreased the expression of Hsp90 and suppressed Akt phosphorylation and NF-κB expression in HepG2 cells. Finally, AGG treatment significantly reduced tumor growth in nude mice bearing HepG2 xenografts, increased TUNEL expression and decreased CD-31 and Ki-67 expression compared to levels observed in the untreated control mice bearing HepG2 cells.
Conclusion: AGG inhibits the growth and progression of HepG2 cells by inducing caspase-mediated cell death. The agglutinin could be an alternative natural remedy for the treatment of human hepatocellular carcinomas.
Keywords: anticancer drug; Abrus agglutinin; hepatocellular carcinoma; apoptosis; caspase; Akt; Hsp90, NF-κB; HepG2 xenografts
We thank the National Institute of Technology, Rourkela and Indian Institute of Technology, Kharagpur, for providing the facility for this research. This research was supported in part by the Rapid Grant for Young Investigator (RGYI) award, Department of Biotechnology, Government of India and Science and Engineering Research Board (SERB), Department of Science and Technology, Government of India. We also acknowledge the input from Debasree Ghosh and Abhishek NANDY, CSIR-SRF fellows of the CSIR-Indian Institute of Chemical Biology, Council of Scientific and Industrial Research, Kolkata, India, who helped to prepare the revised manuscript.
* To whom correspondence should be addressed.
E-mail sujitb@nitrkl.ac.in, bhutiask@gmail.com
Received 2013-07-26 Accepted 2014-01-04
Keywords:
1Department of Life Science, National Institute of Technology, Rourkela, Odisha, India; 2Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal, India
Aim: Abrus agglutinin (AGG) from the seeds of Indian medicinal plant Abrus precatorius belongs to the class II ribosome inactivating protein family. In this study we investigated the anticancer effects of AGG against human hepatocellular carcinoma in vitro and in vivo.
Methods: Cell proliferation, DNA fragmentation, Annexin V binding, immunocytofluorescence, Western blotting, caspase activity assays and luciferase assays were performed to evaluate AGG in human liver cancer cells HepG2. Immunohistochemical staining and TUNEL expression were studied in tumor samples of HepG2-xenografted nude mice.
Results: AGG induced apoptosis in HepG2 cells in a dose- and time-dependent manner. AGG-treated HepG2 cells demonstrated an increase in caspase 3/7, 8 and 9 activities and a sharp decrease in the Bcl-2/Bax ratio, indicating activation of a caspase cascade. Co-treatment of HepG2 cells with AGG and a caspase inhibitor or treatment of AGG in Bax knockout HepG2 cells decreased the caspase 3/7 activity in comparison to HepG2 cells exposed only to AGG. Moreover, AGG decreased the expression of Hsp90 and suppressed Akt phosphorylation and NF-κB expression in HepG2 cells. Finally, AGG treatment significantly reduced tumor growth in nude mice bearing HepG2 xenografts, increased TUNEL expression and decreased CD-31 and Ki-67 expression compared to levels observed in the untreated control mice bearing HepG2 cells.
Conclusion: AGG inhibits the growth and progression of HepG2 cells by inducing caspase-mediated cell death. The agglutinin could be an alternative natural remedy for the treatment of human hepatocellular carcinomas.
Keywords: anticancer drug; Abrus agglutinin; hepatocellular carcinoma; apoptosis; caspase; Akt; Hsp90, NF-κB; HepG2 xenografts
We thank the National Institute of Technology, Rourkela and Indian Institute of Technology, Kharagpur, for providing the facility for this research. This research was supported in part by the Rapid Grant for Young Investigator (RGYI) award, Department of Biotechnology, Government of India and Science and Engineering Research Board (SERB), Department of Science and Technology, Government of India. We also acknowledge the input from Debasree Ghosh and Abhishek NANDY, CSIR-SRF fellows of the CSIR-Indian Institute of Chemical Biology, Council of Scientific and Industrial Research, Kolkata, India, who helped to prepare the revised manuscript.
* To whom correspondence should be addressed.
E-mail sujitb@nitrkl.ac.in, bhutiask@gmail.com
Received 2013-07-26 Accepted 2014-01-04