Induced Oxidative Stress and Cell Death in the A549 Lung Adenocarcinoma Cell Line by Ionizing Radiation Is Enhanced by Supplementation With Docosahexaenoic Acid

Polyunsaturated fatty acids modulate the delivery of platelet microvesicle-derived microRNAs into human breast cancer cell lines

Breast cancer is one of the most frequent and malignant types of cancer in women, with an increasing morbidity and mortality rate; in particular, treatment of triple negative breast cancer remains a challenge, since the efforts made with targeted therapies were ineffective. Among surrounding cells influencing the biology of cancer cells, platelets are recognizing as novel players. Activated platelets release microvesicles (MVs) that, once delivered to cancer cells, modulate signaling pathways related to cell growth and dissemination; among factors contained in platelet-derived MVs, microRNAs are highly involved in cancer development. The growing interest in ω3 and ω6 polyunsaturated fatty acids (PUFAs) as adjuvants in anti-cancer therapy prompted us to investigate the ability of arachidonic acid (AA) and docosahexaenoic acid (DHA) to modulate MV biological functions. AA induced differential enhancement of platelet-specific microRNAs (miR-223 and miR-126), an effect further enhanced by the presence of DHA. MVs can be delivered to and microRNAs internalized by breast cancer cells, although with different efficiency; analysis of kinetics of MV delivery, indeed, suggested that tumor cells fine-tune the uptake of specific microRNA. Finally, we demonstrated that physiological delivery of platelet miR-223 and miR-126 induced cellular effects in breast cancer cells, including cell cycle arrest, inhibition of migration and sensitivity to cisplatin. These results have been confirmed by exogenous expression of miR-223 and miR-126 through transient transfection experiments. Our preliminary data suggest that ω6/ω3-PUFA supplementation, by modulating microRNA delivery, enhances platelet anti-tumor activities, thus opening new avenues for add-on therapies in cancer patients.

MRI reporter gene MagA suppresses transferrin receptor and maps Fe2+ dependent lung cancer

As a magnetic resonance imaging (MRI) reporter gene, MagA has become a powerful tool to monitor dynamic gene expression and allowed concomitant high resolution anatomical and functional imaging of subcellular genetic information. Here we establish a stably expressed MagA method for lung cancer MRI. The results show that MagA can not only enhance both in vitro and in vivo MRI contrast by specifically alternating the transverse relaxation rate of water, but also inhibit the malignant growth of lung tumor. In addition, MagA can regulate magnetic nanoparticle production in grafted tissues and also suppress transferrin receptor expression by acting as an iron transporter, and meanwhile can permit iron biomineralization in the presence of mammalian iron homeostasis. This work provides experimental evidence for the safe preclinical applications of MagA as both a potential inhibitor and an MRI-based tracing tool for iron ion-dependent lung cancer.

Docosahexaenoic acid promotes cell cycle arrest and decreases proliferation through WNT/β-catenin modulation in colorectal cancer cells exposed to γ-radiation

The effects of radiation are known to be potentiated by N-3 polyunsaturated fatty acids, which modulate several signaling pathways, but the molecular mechanisms through which these fatty acids enhance the anticancer effects of irradiation in colorectal cancer (CRC) treatment remain poorly elucidated. Here, we aimed to ascertain whether the fatty acid docosahexaenoic acid (DHA) exerts a modulating effect on the response elicited by radiation treatment (RT). Two CRC cell lines, Caco-2 and HT-29, were exposed to RT, DHA, or both (DHA + RT) for various times, and then cell viability, proliferation, and clonogenicity were assessed. Moreover, cell cycle, apoptosis, and necrosis were analyzed using flow cytometry, and the involvement of WNT/β-catenin signaling was investigated by immunofluorescence to determine nuclear β-catenin, GSK3β phosphorylation status, and TCF/LEF-activity reporter. DHA and RT applied separately diminished the viability of both HT-29 and Caco-2 cells, and DHA + RT caused a further reduction in proliferation mainly in HT-29 cells, particularly in terms of colony formation. Concomitantly, our results verified cell cycle arrest in G0/G1 phase, a reduction of cyclin D1 expression, and a decrease in GSK3β phosphorylation after the combined treatment. Furthermore, immunofluorescence quantification revealed that nuclear β-catenin was increased in RT-exposed cells, but this effect was abrogated in cells exposed to DHA + RT, and the results of TCF/LEF-activity assays confirmed that DHA attenuated the increase in nuclear β-catenin activity induced by irradiation. Our finding shows that DHA applied in combination with RT enhanced the antitumor effects of irradiation on CRC cells, and that the underlying mechanism involved the WNT/β-catenin pathway. © 2018 BioFactors, 45(1):24-34, 2019.

Supplementation with omega fatty acids increases the mRNA expression level of PLA2G4A in patients with gastric cancer

Background

Many lines of evidence suggest that arachidonic acid (AA)-based eicosanoid signaling pathway involved in development and progression of human cancers. Cytosolic phospholipase A2-α (cPLA2α) encoded by the PLA2G4A gene acts as an upstream regulator of eicosanoid signaling pathway through providing intracellular AA. The current study aimed to evaluate the effect of omega fatty acids on mRNA expression level of PLA2G4A in patients with gastric cancer (GC) and to assess the possible relation between its expression and clinicopathological features.

Methods

According to treatment strategy, 34 chemotherapy-naive patients were randomly divided into two groups including, treatment group I (17 subjects received cisplatin alone) and treatment group II (17 individuals received cisplatin plus omega fatty acids) in a double-blind manner. The gastric biopsies specimens were taken from subjects before and after treatment and then mRNA expression level of PLA2G4A was evaluated by quantitative real-time PCR procedure.

Results

The expression of the PLA2G4A gene at the protein level in the gastric biopsies samples was also determined by immunohistochemistry. Our findings revealed a significantly up-regulated expression of PLA2G4A mRNA in treatment group II after receiving cisplatin plus omega fatty acid compared to before treatment (P=0.003). In treatment group I, there was no significant difference in mRNA expression levels of PLA2G4A before and after treatment (P=0.790). We also found that mRNA expression of PLA2G4A in treatment group II was significantly associated with tumor size (P=0.007) and familial history (P=0.006).

Conclusions

This study provides evidence that supplementation with omega fatty acids increases the mRNA expression level of PLA2G4A in patients with GC and may be crucial in guarding the cell from transformation and carcinogenesis.

Docosahexaenoic Acid-mediated Inhibition of Heat Shock Protein 90-p23 Chaperone Complex and Downstream Client Proteins in Lung and Breast Cancer

The molecular chaperone, heat shock protein 90 (Hsp90), is a critical regulator for the proper folding and stabilization of several client proteins, and is a major contributor to carcinogenesis. Specific Hsp90 inhibitors have been designed to target the ATP-binding site in order to prevent Hsp90 chaperone maturation. The current study investigated the effects of docosahexaenoic acid (DHA; C22:6 n-3) on Hsp90 function and downstream client protein expression. In vitro analyses of BT-474 human breast carcinoma and A549 human lung adenocarcinoma cell lines revealed dose-dependent decreases in intracellular ATP levels by DHA treatment, resulting in a significant reduction of Hsp90 and p23 association in both cell lines. Attenuation of the Hsp90-p23 complex led to the inhibition of Hsp90 client proteins, epidermal growth factor receptor 2 (ErbB2), and hypoxia-inducible factor 1α (HIF-1α). Similar results were observed when employing 2-deoxyglucose (2-DG), confirming that DHA and 2-DG, both independently and combined, can disturb Hsp90 molecular chaperone function. In vivo A549 xenograft analysis also demonstrated decreased expression levels of Hsp90-p23 association and diminished protein levels of ErbB2 and HIF-1α in mice supplemented with dietary DHA. These data support a role for dietary intervention to improve cancer therapy in tumors overexpressing Hsp90 and its client proteins.

Omega-3 polyunsaturated fatty acids and cancer: lessons learned from clinical trials

Over the past decades, extensive studies have addressed the therapeutic effects of omega-3 polyunsaturated fatty acids (omega-3 FAs) against different human diseases such as cardiovascular and neurodegenerative diseases, cancer, etc. A growing body of scientific research shows the pharmacokinetic information and safety of these natural occurring substances. Moreover, during recent years, a plethora of studies has demonstrated that omega-3 FAs possess therapeutic role against certain types of cancer. It is also known that omega-3 FAs can improve efficacy and tolerability of chemotherapy. Previous reports showed that suppression of nuclear factor-κB, activation of AMPK/SIRT1, modulation of cyclooxygenase (COX) activity, and up-regulation of novel anti-inflammatory lipid mediators such as protectins, maresins, and resolvins, are the main mechanisms of antineoplastic effect of omega-3 FAs. In this review, we have collected the available clinical data on the therapeutic role of omega-3 FAs against breast cancer, colorectal cancer, leukemia, gastric cancer, pancreatic cancer, esophageal cancer, prostate cancer, lung cancer, head and neck cancer, as well as cancer cachexia. We also discussed the chemistry, dietary source, and bioavailability of omega-3 FAs, and the potential molecular mechanisms of anticancer and adverse effects.

Toxic effects of n-3 polyunsaturated fatty acids in human lung A549 cells

N-3 polyunsaturated fatty acids (PUFAs), particularly eicosapentaenoic acid (EPA, 20:5) and docosahexaenoic acid (DHA, 22:6) are crucial for the prevention of lung cancer. PUFAs may act through alteration of membrane fluidity and cell surface receptor functions; modulation of cyclooxygenase activity; and increased cellular oxidative stress, which may induce apoptosis and autophagy. Therefore the aim of the study was to investigate whether EPA and DHA (25-100 μM) are able to reduce human lung cancer cell growth through oxidative stress influence on autophagy and apoptosis. It was found that both EPA and DHA in the concentration-dependent manner suppressed the cell viability, enhanced cell death, induced activation of caspase-3/7 and potentiated intracellular oxidative DNA and protein damage. In response to PUFAs intracellular autophagic vacuolization occurred and the observed effect was reverted when the autophagy inhibitor 3-methyladenine (3-MA) was applied. The inhibition of the autophagic process enhanced the cell viability, suppressed cell death, and decreased activation of caspase-3/7 indicating that EPA and DHA-induced autophagy amplified A549 apoptotic cell death.

Docosahexaenoic Acid Induces Cell Death in Human Non-Small Cell Lung Cancer Cells by Repressing mTOR via AMPK Activation and PI3K/Akt Inhibition

The anticancer properties and mechanism of action of omega-3 polyunsaturated fatty acids (ω3-PUFAs) have been demonstrated in several cancers; however, the mechanism in lung cancer remains unclear. Here, we show that docosahexaenoic acid (DHA), a ω3-PUFA, induced apoptosis and autophagy in non-small cell lung cancer (NSCLC) cells. DHA-induced cell death was accompanied by AMP-activated protein kinase (AMPK) activation and inactivated phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling. Knocking down AMPK and overexpressing Akt increased mTOR activity and attenuated DHA-induced cell death, suggesting that DHA induces cell death via AMPK- and Akt-regulated mTOR inactivation. This was confirmed in Fat-1 transgenic mice, which produce ω3-PUFAs. Lewis lung cancer (LLC) tumor cells implanted into Fat-1 mice showed slower growth, lower phospho-Akt levels, and higher levels of apoptosis and autophagy than cells implanted into wild-type mice. Taken together, these data suggest that DHA-induced apoptosis and autophagy in NSCLC cells are associated with AMPK activation and PI3K/Akt inhibition, which in turn lead to suppression of mTOR; thus ω3-PUFAs may be utilized as potential therapeutic agents for NSCLC treatment.

Docosahexaenoic acid attenuates breast cancer cell metabolism and the Warburg phenotype by targeting bioenergetic function

Docosahexaenoic acid (DHA; C22:6n-3) depresses mammary carcinoma proliferation and growth in cell culture and in animal models. The current study explored the role of interrupting bioenergetic pathways in BT-474 and MDA-MB-231 breast cancer cell lines representing respiratory and glycolytic phenotypes, respectively and comparing the impacts of DHA with a non-transformed cell line, MCF-10A. Metabolic investigation revealed that DHA supplementation significantly diminished the bioenergetic profile of the malignant cell lines in a dose-dependent manner. DHA enrichment also resulted in decreases in hypoxia-inducible factor (HIF-1α) total protein level and transcriptional activity in the malignant cell lines but not in the non-transformed cell line. Downstream targets of HIF-1α, including glucose transporter 1 (GLUT 1) and lactate dehydrogenase (LDH), were decreased by DHA treatment in the BT-474 cell line, as well as decreases in LDH protein level in the MDA-MB-231 cell line. Glucose uptake, total glucose oxidation, glycolytic metabolism, and lactate production were significantly decreased in response to DHA supplementation; thereby enhancing metabolic injury and decreasing oxidative metabolism. The DHA-induced metabolic changes led to a marked decrease of intracellular ATP levels by 50% in both cancer cell lines, which mediated phosphorylation of metabolic stress marker, AMPK, at Thr172. These findings show that DHA contributes to impaired cancer cell growth and survival by altering cancer cell metabolism, increasing metabolic stress and altering HIF-1α-associated metabolism, while not affecting non-transformed MCF-10A cells. This study provides rationale for enhancement of current cancer prevention models and current therapies by combining them with dietary sources, like DHA.

Key roles for GRB2-associated-binding protein 1, phosphatidylinositol-3-kinase, cyclooxygenase 2, prostaglandin E2 and transforming growth factor alpha in linoleic acid-induced upregulation of lung and breast cancer cell growth

The distribution of omega-6 and omega-3 polyunsaturated fatty acid (PUFA) intake in Western diets is disproportionate, containing an overabundance of the omega-6 PUFA, linoleic acid (LA; C18:2). Increased enrichment with LA has been shown to contribute to the enhancement of tumorigenesis in several cancer models. Previous work has indicated that phosphatidylinositol 3-kinase (PI3K) may play a key role in LA-induced tumorigenesis. However, the modes by which LA affects carcinogenesis have not been fully elucidated. In this study, a mechanism for LA-induced upregulation of cancer cell growth is defined. LA treatment enhanced cellular proliferation in BT-474 human breast ductal carcinoma and A549 human lung adenocarcinoma cell lines. Enrichment of LA increased cyclooxygenase (COX) activity and led to increases in prostaglandin E2 (PGE2), followed by increases in matrix metalloproteinase (MMP) and transforming growth factor alpha (TGF-α) levels, which are all key elements involved in the enhancement of cancer cell growth. Further investigation revealed that LA supplementation in both BT-474 breast and A549 lung cancer cell lines greatly increased the association between the scaffolding protein GRB2-associated-binding protein 1 (Gab1) and epidermal growth factor receptor (EGFR), although Gab1 protein levels were significantly decreased. These LA-induced changes were associated with increases in activated Akt (pAkt), a downstream signaling component in the PI3K pathway. Treatment with inhibitors of EGFR, PI3K and Gab1-specific siRNAs reversed the upregulation of pAkt, as well as the observed increases in cell proliferation by LA in both cell lines. A549 xenograft assessment in athymic nude mice fed high levels of LA exhibited similar increases in EGFR-Gab1 association and increased levels of pAkt, while mice fed with high levels of the omega-3 PUFA, docosahexaenoic acid (DHA; C22:6), demonstrated an opposite response. The involvement of Gab1 in LA-induced tumorigenesis was further defined utilizing murine cell lines that express high levels of Gab1. Significant increases in cell proliferation were observed with the addition of increasing concentrations of LA. However, no changes in cell proliferation were detected in the murine paired cell lines expressing little or no Gab1 protein, establishing Gab1 as major target in LA-induced enhancement of tumorigenesis.

Response of plasma fatty acid profiles to changes in dietary n-3 fatty acids and its correlation with erythrocyte fatty acid profiles in dogs

An elevated level of long-chain n-3 fatty acids (FA) in tissue membranes has a positive influence on the progression and treatment of many diseases. Therefore, dietary supplementation of n-3 FA is recommended in some diseases. Even though n-3 FA are absorbed readily from the diet, their incorporation into tissues may be compromised in diseased animals. In a clinical setting, it is desirable to monitor the success of dietary intervention. Plasma FA as well as erythrocyte membrane (EM) FA can be used to monitor dietary FA intake. This study compares FA from EM and plasma with regard to their reaction time and reliability for monitoring dietary changes of tissue FA profiles in dogs. Thirty dogs were divided into three groups and fed for 12 weeks. The control group (CONT) was fed a commercial standard diet low in n-3 FA. One group received the standard diet and 85 mg/kg body weight of a docosahexaenoic acid (DHA) concentrate (ADD). The third group was fed a commercial dog food containing fish oil (FO), which is rich in eicosapentaenoic acid (EPA). EM and plasma FA profiles were analysed by GC separately. Data on EM FA were published recently. n-3 FA in plasma reached the new level after 2 weeks (8 weeks in EM). Dietary differences between DHA and EPA are obvious after 1 week already. The concomitant decrease in plasma n-6 FA differed between ADD and FO. In general, the correlation of n-6 FA between plasma and EM was low. We therefore conclude that analysis of plasma FA is sufficient for monitoring a diet-induced increase in tissue n-3 FA in dogs. However, EM FA should be analysed if the effect of dietary intervention on tissue n-6 FA is important.

Oxidative stress and lipid peroxidation products in cancer progression and therapy

The generation of reactive oxygen species (ROS) and an altered redox status are common biochemical aspects in cancer cells. ROS can react with the polyunsaturated fatty acids of lipid membranes and induce lipid peroxidation. The end products of lipid peroxidation, 4-hydroxynonenal (HNE), have been considered to be a second messenger of oxidative stress. Beyond ROS involvement in carcinogenesis, increased ROS level can inhibit tumor cell growth. Indeed, in tumors in advanced stages, a further increase of oxidative stress, such as that occurs when using several anticancer drugs and radiation therapy, can overcome the antioxidant defenses of cancer cells and drive them to apoptosis. High concentrations of HNE can also induce apoptosis in cancer cells. However, some cells escape the apoptosis induced by chemical or radiation therapy through the adaptation to intrinsic oxidative stress which confers drug resistance. This paper is focused on recent advances in the studies of the relation between oxidative stress, lipid peroxidation products, and cancer progression with particular attention to the pro-oxidant anticancer agents and the drug-resistant mechanisms, which could be modulated to obtain a better response to cancer therapy.

The janus face of lipids in human breast cancer: how polyunsaturated Fatty acids affect tumor cell hallmarks

For several years, lipids and especially n - 3 and n - 6 polyunsaturated fatty acids (PUFAs) receive much attention in human health. Epidemiological studies tend to correlate a PUFA-rich diet with a reduced incidence of cancer, including breast cancer. However, the molecular and cellular mechanisms supporting the effect of PUFAs in breast cancer cells remain relatively unknown. Here, we review some recent progress in understanding the impact that PUFA may have on breast cancer cell proliferation, apoptosis, migration, and invasion. While most of the results obtained with docosahexaenoic acid and/or eicosapentaenoic acid show a decrease of tumor cell proliferation and/or aggressivity, there is some evidence that other lipids, which accumulate in breast cancer tissues, such as arachidonic acid may have opposite effects. Finally, lipids and especially PUFAs appear as potential adjuvants to conventional cancer therapy.

Multiple roles of dihomo-γ-linolenic acid against proliferation diseases

Considerable arguments remain regarding the diverse biological activities of polyunsaturated fatty acids (PUFA). One of the most interesting but controversial dietary approaches focused on the diverse function of dihomo-dietary γ-linolenic acid (DGLA) in anti-inflammation and anti-proliferation diseases, especially for cancers. This strategy is based on the ability of DGLA to interfere in cellular lipid metabolism and eicosanoid (cyclooxygenase and lipoxygenase) biosynthesis. Subsequently, DGLA can be further converted by inflammatory cells to 15-(S)-hydroxy-8,11,13-eicosatrienoic acid and prostaglandin E₁ (PGE₁). This is noteworthy because these compounds possess both anti-inflammatory and anti-proliferative properties. PGE1 could also induce growth inhibition and differentiation of cancer cells. Although the mechanism of DGLA has not yet been elucidated, it is significant to anticipate the antitumor potential benefits from DGLA.

[Oxidative stress in patients with cancer: two sides of the same coin]

Oxidative stress is a biochemical condition of imbalance between free radicals and antioxidant defence mechanisms. Cancer is an inducing oxidative stress disease. Metabolic changes in neoplastic cells, tumor infiltration by inflammatory cells, malnutrition and specific cancer treatment contribute to high levels of oxidative stress in cancer patients. The toxic effects of oxidative stress on normal cells could be counteracted by use of antioxidants, even though they may abrogate the harmful effects of oxidative stress on tumor cells and prevent apoptosis. Thus, currently, there is not enough scientific evidence to support the use of antioxidants in patients with cancer.

Lung Cancer Survival With Herbal Medicine and Vitamins in a Whole-Systems Approach

Complementary and alternative medicines are used by up to 48% of lung cancer patients but have seen little formal assessment of survival efficacy. In this 10-year retrospective survival study, the authors investigated Pan-Asian medicine + vitamins (PAM+V) therapy in a consecutive case series of all non-small-cell lung cancer patients (n = 239) presenting at a San Francisco Bay Area Chinese medicine center (Pine Street Clinic). They compared short-term treatment lasting the duration of chemotherapy/radiotherapy with long-term therapy continuing beyond conventional therapy. They also compared PAM+V plus conventional therapy with conventional therapy alone, using concurrent controls from the Kaiser Permanente Northern California and California Cancer Registries. They adjusted for confounding with Kaplan-Meier, Cox regression, and newer methods – propensity score and marginal structural models (MSMs), which when analyzing data from observational studies or clinical practice records can provide results comparable with randomized trials. Long-term use of PAM+V beyond completion of chemotherapy reduced stage IIIB deaths by 83% and stage IV by 72% compared with short-term use only for the duration of chemotherapy. Long-term PAM+V combined with conventional therapy reduced stage IIIA deaths by 46%, stage IIIB by 62%, and stage IV by 69% compared with conventional therapy alone. Survival rates for stage IV patients treated with PAM+V were 82% at 1 year, 68% at 2 years, and 14% at 5 years. PAM+V combined with conventional therapy improved survival in stages IIIA, IIIB, and IV, compared with conventional therapy alone. Prospective trials using PAM+V with conventional therapy for lung cancer patients are justified.