Abstract
Background
Colorectal cancer is the third leading cause of cancer-related deaths worldwide, and therefore, the development of novel drugs for its prevention and therapy are urgently required. This study aimed to determine the molecular mechanism of 6,7-dihydroxy-2-(4′-hydroxyphenyl) naphthalene (PNAP-6)-induced cytotoxicity in human colorectal cancer (HCT116) cells.
Methods
The effects of 2-phenylnaphthalene derivatives on HCT116 cell growth and viability were assessed by MTT assays. The mechanisms involved in the regulation of the extrinsic apoptosis and endoplasmic reticulum (ER) stress pathways by PNAP-6 were analyzed by annexin-V/propidium iodide flow cytometric analysis, Hoechst 33342 fluorescent staining, and Western blotting.
Results
PNAP-6 was shown to have an IC50 value 15.20 μM. It induced G2/M phase arrest in HCT116 cells, associated with a marked decrease in cyclin B and CDK1 protein expression and increased caspase activation, PARP cleavage, chromatin condensation, and sub-G1 apoptosis. Moreover, we found that the apoptotic effects of PNAP-6 proceeded through extrinsic apoptosis and ER stress pathways, by increasing the expression of Fas protein and ER stress markers, including PERK, ATF4, CHOP, p-IRE1α, and XBP-1s.
Conclusion
These results suggest that 2-phenylnaphthalene derivatives, such as PNAP-6, have potential as new treatments for colorectal cancer.
Acknowledgments
We would like to acknowledge Dr Ta-Hsien Chuang for providing the compounds (PNAP-1−PNAP-8). We also thank Dr Yang-Chang Wu for kindly providing HCT116 cell lines. This work was financially supported by Ministry of Science and Technology (MOST 104-2321-B-038-012-MY3 and 107-2320-B-038-065), China Medical University (CMU107-SR-104), and the TMU Research Center of Cancer Translational Medicine from The Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE) in Taiwan.
Author contributions
All authors contributed to data analysis, drafting and revising the article, gave final approval of the version to be published, and agree to be accountable for all aspects of the work.
Disclosure
The authors report no conflicts of interest in this work.