Today, colon cancer is the leading cause of cancer death. In Thailand, colon cancer is the third most common cancer in men and the second in women. Currently, the treatments for colon cancer include surgery, chemotherapy, radiation therapy, immunotherapy, hormone therapy, targeted drug therapy, and stem cell therapy. However, some treatments have side effects for cancer patients, causing unwanted symptoms. In addition, targeted therapy comes with a high cost for patients. Therefore, bioactive compounds might be a good choice for colon cancer treatment. In this study, we investigated the effect of artonin E on apoptosis induction in colon cancer LoVo and HCT116 cells. The concentration ranges of artonin E at 3, 5, 10, and 30 µg/mL in LoVo cells and 1, 1.5, 2, and 3 µg/mL in HCT116 cells were examined. The results implied that artonin E decreased cell viability and increased apoptotic cells in a dose-dependent manner. In addition, artonin E stimulated mitochondrial membrane potential (ΔΨm) changes associated with apoptosis by increasing the sub-G1 population analyzed by flow cytometry. Western blotting showed that artonin E increased the proapoptotic protein, Bax, and decreased anti-apoptotic proteins’ (Bcl-2 and Bcl-x) expression. Moreover, artonin E also increased cleaved caspase-7 and cleaved-PARP expression in both LoVo and HCT116 cells. Interestingly, artonin E induced apoptosis through p-ERK1/2, p-p38/p38, and p-c-Jun expression in both cells. Our results suggested that artonin E induced apoptosis via caspase activation associated with the MAPKs signaling pathway. Therefore, artonin E might be used as a potential anticancer drug for colon cancer in the future.

Colon cancer is the most common cause of cancer death in both men and women around the world. The three human RAS genes (KRAS, NRAS and HRAS) are the most frequently mutated oncogenes in human cancer including pancreatic, lung and colon cancers. In particular, KRAS mutated gene prevalently found in pancreas, lung and colon cancer [1]. In colorectal cancer patients, approximately 35-45% mutated KRAS oncogene was reported. The downstream of KRAS associated with survival signaling pathways including Raf/Mek/MAPK and PI3K/Akt [2]. Normally, cancer cell escape death induction by upregulation of Raf/Mek/MAPK and PI3K/Akt activity. Thus, inhibition of Raf/Mek/MAPK and PI3K/Akt signaling pathway is necessary. Nowadays, treatment of colon cancer is quite limited due to the high cost and side effects, therefore, bioactive compound therapy might be the choice for development of colon cancer treatment. In this study, we investigate the effect of artonin E on apoptosis induction in colon cancer HCT116 cells. Nuclear morphological changes and the loss of mitochondrial membrane potential, characteristics of apoptosis induction were determined by Hoechst 33342 staining and JC-1 staining, respectively. Mediator proteins that associated with apoptosis induction and signaling molecules were determined by Western blot analysis. Our results indicated that artonin E induced apoptotic bodies and loss of mitochondrial membrane potential in HCT116 treated cells. In addition, artonin E showed upregulation of cleave-caspase-7 (active form) and cleave-PARP (inactive form), mediator of apoptosis induction, in HCT116 cells. Moreover, artonin E reduced Akt and increased p-ERK1/2 expression in HCT116 cells. This data correlated with previous study by Tangchirakhaphan et al and Bee-Jen Tan et al, that ERK1/2 could activate caspase and pro-apoptotic protein in Bcl-2 family. Moreover, ERK1/2 could deactivate Akt signaling pathway leading to apoptosis induction [3,4]. Our study indicated that artonin E induced apoptosis cell death through p-ERK1/2 upregulation and may be used as a potential therapeutic candidate in the future. Keywords: Artonin E, Apoptosis, Colon cancer, KRAS [1] Cox AD, Fesik SW, Kimmelman AC, Luo J, Der CJ. Drugging the undruggable RAS: Mission possible? Nat Rev Drug Discov. 2014;13(11):828-51. [2] Eser S, Schnieke A, Schneider G, Saur D. Oncogenic KRAS signalling in pancreatic cancer. Br J Cancer. 2014;111(5):817-22. [3] Tangchirakhaphan S, Innajak S, Nilwarangkoon S, Tanjapatkul N, Mahabusrakum W, Watanapokasin R. Mechanism of apoptosis induction associated with ERK1/2 upregulation via goniothalamin in melanoma cells. Exp Ther Med. 2018;15(3):3052-8. [4] Tan BJ, Chiu GN. Role of oxidative stress, endoplasmic reticulum stress and ERK activation in triptolide-induced apoptosis. Int J Oncol. 2013;42(5):1605-12. Citation Format: Supichaya Nimnuan-ngam, Kanyaluck Yangnok, Sukanda Innajak, Ramida Watanapokasin. Effect of artonin E on apoptosis cell death induction in colon cancer cell [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr B061.