The omega-3 DHA induces pyroptosis and mitochondrial dysfunction in ovarian cancer cells via ROS and caspase-1 activation

The role of omega-3 long-chain polyunsaturated fatty acids in health and disease of the retina.

Antiretroviral nucleoside and nucleotide analogues and mitochondria.

Influencing mitochondrial membrane composition and bioenergetics through omega-3 supplementation.

Increased preconception omega-3 polyunsaturated fatty acid intake improves embryo morphology

We have established that docosahexaenoic acid (DHA), the major polyunsaturated fatty acid in the retina, promotes survival of rat retina photoreceptors during early development in vitro and upon oxidative stress by activating the ERK/MAPK signaling pathway. Here we have investigated whether DHA turns on this pathway through activation of retinoid X receptors (RXRs) or by inducing tyrosine kinase (Trk) receptor activation. We also evaluated whether DHA release from phospholipids was required for its protective effect. Addition of RXR antagonists (HX531, PA452) to rat retinal neuronal cultures inhibited DHA protection during early development in vitro and upon oxidative stress induced with Paraquat or H2O2. In contrast, the Trk inhibitor K252a did not affect DHA prevention of photoreceptor apoptosis. These results imply that activation of RXRs was required for DHA protection whereas Trk receptors were not involved in this protection. Pretreatment with 4-bromoenol lactone, a phospholipase A2 inhibitor, blocked DHA prevention of oxidative stress-induced apoptosis of photoreceptors. It is noteworthy that RXR agonists (HX630, PA024) also rescued photoreceptors from H2O2-induced apoptosis. These results provide the first evidence that activation of RXRs prevents photoreceptor apoptosis and suggest that DHA is first released from phospholipids and then activates RXRs to promote the survival of photoreceptors.

Although abundant experimental evidences show that the Omega-3 polyunsaturated fatty acids (≥3-PUFAs) prevent carcinogenesis, the exact molecular mechanisms of the anti-cancer actions of α3-PUFAs in ovarian cancer remain incompletely understood. In the present study, the effectiveness of docosahexaenoic acid (DHA), a α3-PUFA, against ovarian cancer cells was investigated. We found that DHA induced cell cytotoxicity in three ovarian cancer cells including PA-1, MDAH2774 and ID8. DHA treatment inhibited the cell proliferation of PA-1 cells in a dose- and time-dependent manner. Meanwhile, DHA-treated ovarian cancer cells showed increased levels of caspase-3 activity, Annexin-V staining positive cells, TUNEL-positive cells and the portion of sub-G1 cells, suggesting that DHA-induced cell death is mainly associated with apoptosis. Western blot and immunocytochemistry assays revealed that DHA also remarkably increased the levels of phospho-ERK and phospho-JNK in both cytosol and nucleus. Moreover, knockdown ERK and JNK by small interfering RNAs partially attenuated the apoptosis induced by DHA, indicating that ERK and JNK activation is responsible for the apoptosis in DHA-treated ovarian cancer cells. In addition, we determined that the activation of ERK and JNK was associated with the reactive oxygen species (ROS) production induced by DHA. ROS scavenger, N-acetyl-L-cysteine (NAC), almost completely blocked the ERK and JNK phosphorylation as well as the apoptosis triggered by DHA. Together, these results indicate that DHA induces ROS and the ROS-dependent ERK and JNK activation is important to DHA-induced cell cytotoxicity in human ovarian cancer cells. [This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2011-0006232 and 2011-0003060)]. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4175. doi:1538-7445.AM2012-4175

Do mitochondria care about insulin resistance?

Enzymes scavenging reactive oxygen species (ROS) are important for cell protection during stress and aging. A deficiency in these enzymes leads to ROS imbalance, causing various disorders in many organisms, including yeast. In contrast to liquid cultures, where fitness of the yeast population depends on its ROS scavenging capability, the present study suggests that Saccharomyces cerevisiae cells growing in colonies capable of ammonia signaling use a broader protective strategy. Instead of maintaining high levels of antioxidant enzymes for ROS detoxification, colonies activate an alternative metabolism that prevents ROS production. Colonies of the strain deficient in cytosolic superoxide dismutase Sod1p thus developed the same way as wild type colonies. They produced comparable levels of ammonia and underwent similar developmental changes (expression of genes of alternative metabolism and center margin differentiation in ROS production, cell death occurrence, and activities of stress defense enzymes) and did not accumulate stress-resistant suppressants. An absence of cytosolic catalase Ctt1p, however, brought colonies developmental problems, which were even more prominent in the absence of mitochondrial Sod2p. sod2Delta and ctt1Delta colonies failed in ammonia production and sufficient activation of the alternative metabolism and were incapable of center margin differentiation, but they did not increase ROS levels. These new data indicate that colony disorders are not accompanied by ROS burst but could be a consequence of metabolic defects, which, however, could be elicited by imbalance in ROS produced in early developmental phases. Sod2p and homeostasis of ROS may participate in regulatory events leading to ammonia signaling.

Effects of ROS pathway inhibitors and NADH and FADH2 linked substrates on mitochondrial bioenergetics and ROS emission in the heart and kidney cortex and outer medulla

B-cell lymphoma-extra large (Bcl-xL) is an anti-apoptotic member of the Bcl2 family of proteins, which supports neurite outgrowth and neurotransmission by improving mitochondrial function. During excitotoxic stimulation, however, Bcl-xL undergoes post-translational cleavage to ∆N-Bcl-xL, and accumulation of ∆N-Bcl-xL causes mitochondrial dysfunction and neuronal death. In this study, we hypothesized that the generation of reactive oxygen species (ROS) during excitotoxicity leads to formation of ∆N-Bcl-xL. We further proposed that the application of an antioxidant with neuroprotective properties such as α-tocotrienol (TCT) will prevent ∆N-Bcl-xL-induced mitochondrial dysfunction via its antioxidant properties. Primary hippocampal neurons were treated with α-TCT, glutamate, or a combination of both. Glutamate challenge significantly increased cytosolic and mitochondrial ROS and ∆N-Bcl-xL levels. ∆N-Bcl-xL accumulation was accompanied by intracellular ATP depletion, loss of mitochondrial membrane potential, and cell death. α-TCT prevented loss of mitochondrial membrane potential in hippocampal neurons overexpressing ∆N-Bcl-xL, suggesting that ∆N-Bcl-xL caused the loss of mitochondrial function under excitotoxic conditions. Our data suggest that production of ROS is an important cause of ∆N-Bcl-xL formation and that preventing ROS production may be an effective strategy to prevent ∆N-Bcl-xL-mediated mitochondrial dysfunction and thus promote neuronal survival.

Targeting multiple mediators of sepsis using multifunctional tannic acid-Zn2+-gentamicin nanoparticles

Physical Activity, Omega-3 Supplements No Cognitive Panacea

The omega-3 fatty acid, docosahexaenoic acid (DHA), has been shown to induce the proteasomal degradation of various cancer-associated molecules such as beta-catenin and estrogen receptor, implying its regulatory effect on proteasome. To verify this possible link between DHA and proteasome function, we explored the impacts of DHA on human papillomavirus-positive HeLa cervical cancer cells that constitutively express two known endogenous proteasome substrates E6 and E7 viral proteins. Exposure HeLa cells to DHA resulted in elevated proteasome activities along with decreased levels of E6/E7 viral proteins, and these effects of DHA were remarkably reversed in the presence of proteasome inhibitors, suggesting that DHA improves proteasome function in the cells and thereby accelerates the degradation of proteasome substrates. The DHA-induced increase in cellular proteasome activity was preceded by reactive oxygen species (ROS) overproduction and could be blocked by preincubation of the cells with ROS scavengers. Likewise, HeLa cells treated with exogenous ROS, H2O2, also exhibited significantly improved proteasome function. Unexpectedly, when the purified proteasome and whole-cell lysates isolated from HeLa cells were directly exposed to DHA or H2O2, such marked increases in proteasome activity were not seen. Taken together, these findings indicate that DHA may induce proteasome activation in cervical cancer cells mainly by indirect regulation of the proteasome. Citation Format: Kyu Lim, Kaipeng Jing, Soyeon Shin, Soyeon Jeong, Soyeon Kim, Gi-Ryang Kweon, Seung-Kiel Park, Tong Wu, Jong-Il Park. DHA may enhance proteasome activity in human cervical cancer cells: Indirect modulation of proteasome by DHA. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2255. doi:10.1158/1538-7445.AM2014-2255

The evolving role of mitochondria in metabolism

BackgroundOmega-3 long chain-polyunsaturated fatty acids (LC-PUFAs)–docosahexaenoic acid (DHA), docosapentaenoic acid (DPA) and eicosapentaenoic acid (EPA)– and omega-6 LC-PUFA arachidonic acid (ARA), are essential for optimum physical and mental development in children. Prior to this study, the blood omega-3 LC-PUFA levels were unknown in Zimbabwean children, particularly in those aged 7–9 years, despite the documented benefits of LC-PUFAs. Documentation of the LC-PUFA levels in this age group would help determine whether interventions, such as fortification, are necessary. This study aimed to determine dried whole blood spot omega-3 and omega-6 LC-PUFA levels and LC-PUFA reference intervals among a selected group of Zimbabwean children aged 7–9 years old.MethodsWe conducted a cross sectional study from September 2011 to August 2012 on a cohort of peri-urban, Zimbabwean children aged 7–9 years. The children were born to mothers enrolled at late pregnancy into an HIV prevention program between 2002 and 2004. Dried whole blood spots were sampled on butylated hydroxytoluene antioxidant impregnated filter papers and dried. LC-PUFAs were quantified using gas liquid chromatography. Differences in LC-PUFAs between groups were compared using the Kruskal Wallis test and reference intervals determined using non-parametric statistical methods.ResultsLC-PUFAs levels were determined in 297 Zimbabwean children of whom 170 (57.2 %) were girls. The study determined that LC-PUFAs (wt/wt) ranges were EPA 0.06–0.55 %, DPA 0.38–1.98 %, DHA 1.13–3.52 %, ARA 5.58–14.64 % and ARA: EPA ratio 15.47–1633.33. Sixteen participants had omega-3 LC-PUFAs levels below the determined reference intervals, while 18 had higher omega-6 LC-PUFAs. The study did not show gender differences in omega-3 and omega-6 LC-PUFAs levels (all p > 0.05). EPA was significantly higher in the 8 year age group compared to those aged 7 and 9 years (median; 0.20 vs 0.17 vs 0.18, respectively, p = 0.049). ARA: EPA ratio was significantly higher in the 7 year age group compared to those aged 8 and 9 years (median; 64.38 vs 56.43 vs 55.87 respectively, p = 0.014).ConclusionsIn this cohort of children, lower EPA levels and higher ARA: EPA ratios were observed compared to those reported in apparently healthy children elsewhere. The high ARA: EPA ratios might increase the vulnerability of these children to inflammatory pathologies. Identification and incorporation into diet of locally produced foodstuffs rich in omega-3 LC-PUFAs is recommended as well as advocating for dietary supplementation with omega-3 fish oils and algae based oils.