Role of autophagy in the ω-3 long chain polyunsaturated fatty acid-induced death of lung cancer A549 cells

Abstract

Abstract. The present study identified that ω-3 long chain polyunsaturated fatty acids (ω-3 PUFAs), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) demonstrate anti-proliferative effects in lung cancer A549 cells. MTS and cytotoxicity assays were conducted to confirm that ω-3 PUFAs induced cell death. Autophagy-associated gene and signaling pathways were also detected. Microtubule-associated protein light chain 3 (LC3) expression was found to be increased subsequent to treatment with DHA and EPA, and the expression of LC3-II was particularly increased. mRFP-GFP-LC3 fluorescence staining and p62 expression levels were used to detect autophagic flux. The present results indicate that DHA and EPA block autophagic flux, suggesting autophagosome accumulation. Subsequent to treatment with DHA and EPA, which interfered with autophagosomes, the expression of Beclin 1 was significantly decreased, while the expression of phosphorylated Akt and phosphorylated mammalian target of rapamycin was significantly increased. Therefore, DHA and EPA exert anti-proliferative effects by inhibiting autophagy in A549 cells, which highlights the potential of DHA and EPA for use in the prevention or treatment of lung cancer. IntroductionLung cancer is the leading cause of cancer-associated mortality worldwide (1), and the five-year survival rate remains extremely poor (2). Overall, ~75-85% of lung cancers cases are non-small cell lung cancer (NSCLC), which includes squamous cell carcinoma, adenocarcinoma and large cell carcinoma. The treatment of lung cancer involves the use of medical therapies such as surgery, radiation, chemotherapy and palliative care (3) in an attempt to successfully treat or reduce the adverse impact of malignant neoplasms originating in lung tissue. Chemotherapeutic agents are the main treatment measures for NSCLC, but the side-effects are usually difficult to tolerate (4).Fish oils are an excellent source of long-chain ω-3 polyunsaturated fatty acids (ω-3 PUFAs), including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Fish oil supplements are increasingly recognized by clinical studies to be useful for the treatment of a variety of human afflictions, including cancer (5). Numerous studies reveal evidence for the capability of ω-3 PUFAs to decrease proliferation, exert a pro-apoptotic effect and inhibit angiogenesis in several in vitro models of colon cancer (6-9).A previous study indicated that DHA and EPA inhibit the proliferation of A549 cells and induce apoptosis, with autophagy also being observed under transmission electron microscopy (10). Autophagy is a type of programmed cell death and it is an important process that is involved in various human pathologies. Previous studies suggest that autophagy is important in the regulation of cancer development and progression and also in determining the response of tumor cells to anticancer therapy (11)(12)(13)(14). Several cell signaling pathways are implicated in regulating autophagy, including the phosphatidyl inositol 3-kinase (PI3K)/Akt/...

SWATH Differential Abundance Proteomics and Cellular Assays Show In Vitro Anticancer Activity of Arachidonic Acid- and Docosahexaenoic Acid-Based Monoacylglycerols in HT-29 Colorectal Cancer Cells

“…The findings of this work outline other ones from Ramos Bueno et al [24], who demonstrated that unspecific oil-derived ARASCO ®and DHASCO ® -MAG induced noticeable in vitro antitumor activity on HT-29 cells. Previous studies demonstrated that DHA significantly decreases cancer cells proliferation [28]; while Pompeia et al [12] found dose-and time-dependent ARA-induced cytotoxicity in leukocytes, i.e., ARA at 10-400 µM induced apoptosis, while at concentrations above 400 µM the noted effect was necrosis. Several studies have discussed the relationship between FAs and mitochondrial permeability transition.…”

Metabolic Shift Induced by ω -3 PUFAs and Rapamycin Lead to Cancer Cell Death

“…In response to environmental stresses (e.g., nutrient starvation, hypoxia, infections), autophagy is upregulated to provide the energy supply needed for cell survival and repair [28], and recent studies have shown that the induction of autophagy facilitates cancer cell resistance to Rp-induced apoptosis [29]. Previous studies [19,30]. Thus, we determined whether autophagy plays a key role in the synergistic effects caused by ω-3 PUFA+Rp combination treatment.…”

Dihydroartemisinin and its anticancer activity against endometrial carcinoma and cervical cancer: involvement of apoptosis, autophagy and transferrin receptor

“…Autophagy plays a dual role in cell survival. (22) We showed that inhibition of autophagy further enhanced cell death, suggesting a cytoprotective function for DHA-induced activation of autophagy. By blocking the autophagy pathway using 3-MA and reducing DHA-induced cancer death, we concluded that the DHA effect against tumour cells was mediated through the autophagy pathway.…”