Eicosapentaenoic Acid Inhibits <i>KRAS</i> Mutant PancreaticCancer Cell Growth by Suppressing Hepassocin Expression and STAT3 Phosphorylation

• Main Authors: Ching-Feng Chiu, Ming-I Hsu, Hsiu-Yen Yeh, Ji Min Park, Yu-Shiuan Shen, Te-Hsuan Tung, Jun-Jie Huang, Hung-Tsung Wu, Shih-Yi Huang
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Biomolecules
• Subjects: pancreatic cancer; <i>KRAS</i> mutation; hepassocin; eicosapentaenoic acid
• Online Access: https://www.mdpi.com/2218-273X/11/3/370

Background: The oncogenic Kirsten rat sarcoma viral oncogene homolog (<i>KRAS</i>) mutation was reported to be the signature genetic event in most cases of pancreatic ductal adenocarcinoma (PDAC). Hepassocin (HPS/FGL1) is involved in regulating lipid metabolism and the progression of several cancer types; however, the underlying mechanism of HPS/FGL1 in the <i>KRAS</i> mutant PDAC cells undergoing eicosapentaenoic acid (EPA) treatment remains unclear. Methods: We measured HPS/FGL1 protein expressions in a human pancreatic ductal epithelial (HPNE) normal pancreas cell line, a <i>KRAS</i>-wild-type PDAC cell line (BxPC-3), and <i>KRAS</i>-mutant PDAC cell lines (PANC-1, MIA PaCa-2, and SUIT-2) by Western blot methods. HEK293T cells were transiently transfected with corresponding <i>KRAS</i>-expressing plasmids to examine the level of HPS expression with <i>KRAS</i> activation. We knocked-down HPS/FGL1 using lentiviral vectors in SUIT-2 cells and measured the cell viability by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and clonogenicity assays. Furthermore, a lipidomic analysis was performed to profile changes in lipid metabolism after HPS/FGL1 knockdown. Results: We found that the HPS/FGL1 level was significantly upregulated in <i>KRAS</i>-mutated PDAC cells and was involved in <i>KRAS</i>/phosphorylated (p)-signal transduction and activator of transcription 3 (STAT3) signaling, and the knockdown of HPS/FGL1 in SUIT-2 cells decreased cell proliferation through increasing G₂/M cell cycle arrest and cyclin B1 expression. In addition, the knockdown of HPS/FGL1 in SUIT-2 cells significantly increased omega-3 polyunsaturated fatty acids (PUFAs) and EPA production but not docosahexaenoic acid (DHA). Moreover, EPA treatment in SUIT-2 cells reduced the expression of de novo lipogenic protein, acetyl coenzyme A carboxylase (ACC)-1, and decreased p-STAT3 and HPS/FGL1 expressions, resulting in the suppression of cell viability. Conclusions: Results of this study indicate that HPS is highly expressed by <i>KRAS</i>-mutated PDAC cells, and HPS/FGL1 plays a crucial role in altering lipid metabolism and increasing cell growth in pancreatic cancer. EPA supplements could potentially inhibit or reduce ACC-1-involved lipogenesis and HPS/FGL1-mediated cell survival in <i>KRAS</i>-mutated pancreatic cancer cells.