Antiangiogenicity of docosahexaenoic acid and its role in the suppression of breast cancer cell growth in nude mice

Natural products‐based antiangiogenic agents: New frontiers in cancer therapy

Angiogenesis, vital for tumor growth and metastasis, is a promising target in cancer therapy. Natural compounds offer potential as antiangiogenic agents with reduced toxicity. This review provides a comprehensive overview of natural product‐based antiangiogenic therapies, focusing on molecular mechanisms and therapeutic potential. A systematic search identified relevant articles from 2019 to 2023. Various natural compounds, including polyphenols, terpenes, alkaloids, cannabinoids, omega‐3 fatty acids, polysaccharides, proteins, and carotenoids, were investigated for their antiangiogenic properties. Challenges such as dose standardization, routes of administration, and potential side effects remain. Further studies, including in‐depth animal models and human epidemiological studies, must elucidate clinical efficacy and safety. Synergistic effects with current antiangiogenic therapies, such as bevacizumab and tyrosine kinase inhibitors, should be explored. Additionally, the potential hormone‐dependent effects of compounds like genistein highlight the need for safety evaluation. In conclusion, natural products hold promise as adjunctive therapies to conventional antineoplastic drugs in modulating angiogenesis in cancer. However, robust clinical trials are needed to validate preclinical findings and ensure safety and efficacy.

Contribution of n-3 Long-Chain Polyunsaturated Fatty Acids to the Prevention of Breast Cancer Risk Factors

Nowadays, diet and breast cancer are studied at different levels, particularly in tumor prevention and progression. Thus, the molecular mechanisms leading to better knowledge are deciphered with a higher precision. Among the molecules implicated in a preventive and anti-progressive way, n-3 long chain polyunsaturated fatty acids (n-3 LC-PUFAs) are good candidates. These molecules, like docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids, are generally found in marine material, such as fat fishes or microalgae. EPA and DHA act as anti-proliferative, anti-invasive, and anti-angiogenic molecules in breast cancer cell lines, as well as in in vivo studies. A better characterization of the cellular and molecular pathways involving the action of these fatty acids is essential to have a realistic image of the therapeutic avenues envisaged behind their use. This need is reinforced by the increase in the number of clinical trials involving more and more n-3 LC-PUFAs, and this, in various pathologies ranging from obesity to a multitude of cancers. The objective of this review is, therefore, to highlight the new elements showing the preventive and beneficial effects of n-3 LC-PUFAs against the development and progression of breast cancer.

15-Lipoxygenase and its metabolites in the pathogenesis of breast cancer: A double-edged sword

15-lipoxygenase is one of the key enzymes for the metabolism of unsaturated fatty acids that its manipulation has been proposed recently as a new molecular target for regulating cancer cell growth. Aberrant expression of 15-lipoxygenase enzyme seems to play an indicative role in the pathology of different cancer types, tumor progression, metastasis, or apoptosis. Based on the fact that breast cancer is one of the most common cancers that imposes a burden of mortality in women also, on the other hand, evidence in experimental models and human studies indicate the emerging role of the 15-lipoxygenase pathway in breast cancer pathogenesis, we present a review of recent findings related to the role of 15- lipoxygenase enzyme and metabolites in breast cancer growth, apoptosis, metastasis, and invasion as well as their local and circulating expression pattern in patients with breast cancer. Our review supports the emerging role of 15- lipoxygenase in molecular and cellular processes regulating breast tumor cell fate with both positive and negative effects.

Targeting ferroptosis in breast cancer

Ferroptosis is a recently discovered distinct type of regulated cell death caused by the accumulation of lipid-based ROS. Metabolism and expression of specific genes affect the occurrence of ferroptosis, making it a promising therapeutic target to manage cancer. Here, we describe the current status of ferroptosis studies in breast cancer and trace the key regulators of ferroptosis back to previous studies. We also compare ferroptosis to common regulated cell death patterns and discuss the sensitivity to ferroptosis in different subtypes of breast cancer. We propose that viewing ferroptosis-related studies from a historical angle will accelerate the development of ferroptosis-based biomarkers and therapeutic strategies in breast cancer.

EPA and DHA Fatty Acids Induce a Remodeling of Tumor Vasculature and Potentiate Docetaxel Activity

n-3 long chain Polyunsaturated Fatty Acids (n-3 LCPUFA) have been shown to improve the efficacy of conventional chemotherapies used for breast cancer treatment. In addition to their reported ability to increase the chemosensitivity of cancer cells, we hypothesized that n-3 LCPUFA could induce a remodeling of the vascular network in mammary tumors. A contrast-enhanced ultrasound method was used to monitor the vascular architecture during docetaxel treatment of mammary tumors in rats fed either a control or an n-3 LCPUFA-enriched diet (docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA)). The vascular network was remodeled in favor of smaller vessels (microvascularization), which represented 54% of the vasculature in n-3 LCPUFA tumors but only 26% in control tumors after 2 weeks of chemotherapy. Importantly, vascularization changes occurred both before and during docetaxel treatment. The density of smaller vessels quantified before chemotherapy was correlated with improved tumor size reduction by docetaxel treatment. Furthermore, transcript levels of the angiogenesis-specific genes epiregulin and amphiregulin were reduced by ~4.5- and twofold in tumors obtained from rats fed an n-3 LCPUFA-enriched diet compared to those of rats fed a control diet, respectively. Their expression levels were negatively correlated with tumor regression after chemotherapy. Taken together, this preclinical data strengthen the potential usefulness of n-3 LCPUFA as a complementary clinical strategy to improve drug efficiency via remodeling of the tumor vasculature.

Fatty acids distribution and content in oral squamous cell carcinoma tissue and its adjacent microenvironment

Squamous cell carcinoma of the oral cavity mucosa grows under conditions of poor oxygenation and nutrient scarcity. Reprogramming of lipid biosynthesis accompanies tumor growth, but the conditions under which it occurs are not fully understood. The fatty acid content of the serum, tumor tissue and adjacent tumor microenvironment was measured by gas chromatography in 30 patients with squamous cell carcinoma grade 1-3. Twenty-five fatty acids were identified; their frequencies and percentages in each of the environments were assessed. Nineteen of the twenty-five fatty acids were found in tumor tissue, tumor adjacent tissue and blood serum. Of them, 8 were found in all thirty patients. Percentages of C16:0 and C18:1n9 were highest in the tumor, C18:1n9 and C16:0 were highest in tumor adjacent tissue, and C16:0 and C18:0 were highest in blood serum. The frequencies and amounts of C22:1n13, C22:4n6, C22:5n3 and C24:1 in tumor adjacent tissues were higher than those in blood serum, independent of the tumor grade. The correlations between the amount of fatty acid and tumor grade were the strongest in tumor adjacent tissues. The correlations between particular fatty acids were most prevalent for grade 1+2 tumors and were strongest for grade 3 tumors. In the adjacent tumor microenvironment, lipogenesis was controlled by C22:6w3. In blood serum, C18:1trans11 limited the synthesis of long-chain fatty acids. Our research reveals intensive lipid changes in oral cavity SCC adjacent to the tumor microenvironment and blood serum of the patients. Increase in percentage of some of the FAs in the path: blood serum-tumor adjacent microenvironment-tumor, and it is dependent on tumor grade. This dependency is the most visible in the tumor adjacent environment.

Docosahexaenoic Acid Inhibits Vascular Smooth Muscle Cell Proliferation Induced by Glucose Variability

Background:

Vascular Smooth Muscle cells (VSMC) enact crucial roles in early vasculogenesis and sustenance of vascular integrity. However, aberrant proliferation of VSMC followed by migration into the blood vessel wall leads to the formation of vascular lesions accounting for the degeneration and remodelling of vascular basement membrane. In diabetes, hyperglycaemia accelerates VSMC proliferation and contributes to the initiation and progression of atherosclerotic lesions. Recently, acute glucose fluctuations have been implicated in the abnormal VSMC proliferation and complications of diabetic atherosclerosis. Docosahexaenoic acid (DHA), a ω-3 polyunsaturated fatty acid (PUFA) has been shown to inhibit proliferation of several cell types implicating several different mechanisms. In the present study, we have investigated the effects of DHA on VSMC proliferation induced by stable and intermittent high glucose levels.

Method:

Confluent cultures of rat aortic VSMCs were treated with DHA for 24 hrs and then exposed to stable high glucose (25 mmol/L, SHG) or intermittent high glucose (5 mmol/L and 25 mmol/L alternating every 12 hrs, IHG) for 72 hrs. Cell proliferation was examined by the MTT viability assay, while apoptosis process was evaluated by the Hoechst staining, flow cytometry and caspase-3 activity assays.

Results:

Our data demonstrated that the hyper proliferation induced by stable and intermittent high glucose levels was significantly inhibited by the DHA pre-treatment. DHA significantly increased caspase-3 activity, resulting in enhanced DNA fragmentation and apoptosis.

Conclusion:

Our results suggest that DHA reduced the high glucose-induced proliferation of VSMC and induced cell apoptosis.

Exosome-mediated microRNA signaling from breast cancer cells is altered by the anti-angiogenesis agent docosahexaenoic acid (DHA)

BACKGROUND

Docosahexaenoic acid (DHA) is a natural compound with anticancer and anti-angiogenesis activity that is currently under investigation as both a preventative agent and an adjuvant to breast cancer therapy. However, the precise mechanisms of DHA's anticancer activities are unclear. It is understood that the intercommunication between cancer cells and their microenvironment is essential to tumor angiogenesis. Exosomes are extracellular vesicles that are important mediators of intercellular communication and play a role in promoting angiogenesis. However, very little is known about the contribution of breast cancer exosomes to tumor angiogenesis or whether exosomes can mediate DHA's anticancer action.

RESULTS

Exosomes were collected from MCF7 and MDA-MB-231 breast cancer cells after treatment with DHA. We observed an increase in exosome secretion and exosome microRNA contents from the DHA-treated cells. The expression of 83 microRNAs in the MCF7 exosomes was altered by DHA (>2-fold). The most abundant exosome microRNAs (let-7a, miR-23b, miR-27a/b, miR-21, let-7, and miR-320b) are known to have anti-cancer and/or anti-angiogenic activity. These microRNAs were also increased by DHA treatment in the exosomes from other breast cancer lines (MDA-MB-231, ZR751 and BT20), but not in exosomes from normal breast cells (MCF10A). When DHA-treated MCF7 cells were co-cultured with or their exosomes were directly applied to endothelial cell cultures, we observed an increase in the expression of these microRNAs in the endothelial cells. Furthermore, overexpression of miR-23b and miR-320b in endothelial cells decreased the expression of their pro-angiogenic target genes (PLAU, AMOTL1, NRP1 and ETS2) and significantly inhibited tube formation by endothelial cells, suggesting that the microRNAs transferred by exosomes mediate DHA's anti-angiogenic action. These effects could be reversed by knockdown of the Rab GTPase, Rab27A, which controls exosome release.

CONCLUSIONS

We conclude that DHA alters breast cancer exosome secretion and microRNA contents, which leads to the inhibition of angiogenesis. Our data demonstrate that breast cancer exosome signaling can be targeted to inhibit tumor angiogenesis and provide new insight into DHA's anticancer action, further supporting its use in cancer therapy.

Omega-3 polyunsaturated fatty acids enhance cerebral angiogenesis and provide long-term protection after stroke

Stroke is a devastating neurological disorder and one of the leading causes of death and serious disability. After cerebral ischemia, revascularization in the ischemic boundary zone provides nutritive blood flow as well as various growth factors to promote the survival and activity of neurons and neural progenitor cells. Enhancement of angiogenesis and the resulting improvement of cerebral microcirculation are key restorative mechanisms and represent an important therapeutic strategy for ischemic stroke. In the present study, we tested the hypothesis that post-stroke angiogenesis would be enhanced by omega-3 polyunsaturated fatty acids (n-3 PUFAs), a major component of dietary fish oil. To this end, we found that transgenic fat-1 mice that overproduce n-3 PUFAs exhibited long-term behavioral and histological protection against transient focal cerebral ischemia (tFCI). Importantly, fat-1 transgenic mice also exhibited robust improvements in revascularization and angiogenesis compared to wild type littermates, suggesting a potential role for n-3 fatty acids in post-stroke cerebrovascular remodeling. Mechanistically, n-3 PUFAs induced upregulation of angiopoietin 2 (Ang 2) in astrocytes after tFCI and stimulated extracellular Ang 2 release from cultured astrocytes after oxygen and glucose deprivation. Ang 2 facilitated endothelial proliferation and barrier formation in vitro by potentiating the effects of VEGF on phospholipase Cγ1 and Src signaling. Consistent with these findings, blockade of Src activity in post-stroke fat-1 mice impaired n-3 PUFA-induced angiogenesis and exacerbated long-term neurological outcomes. Taken together, our findings strongly suggest that n-3 PUFA supplementation is a potential angiogenic treatment capable of augmenting brain repair and improving long-term functional recovery after cerebral ischemia.

Matrix metalloproteinase (MMP)-9 in cancer-associated fibroblasts (CAFs) is suppressed by omega-3 polyunsaturated fatty acids in vitro and in vivo

Cancer associated fibroblasts (CAFs) are responsible for tumor growth, angiogenesis, invasion, and metastasis. Matrix metalloproteinase (MMP)-9 secreted from cancer stroma populated by CAFs is a prerequisite for cancer angiogenesis and metastasis. Omega-3 polyunsaturated fatty acids (omega-3 PUFA) have been reported to have anti-tumor effects on diverse types of malignancies. Fat-1 mice, which can convert omega-6 to omega-3 PUFA independent of diet, are useful to investigate the functions of endogenous omega-3 PUFA. To examine the effect of omega-3 PUFA on tumorigenesis, TC-1 cells, a murine epithelial cell line immortalized by human papillomavirus (HPV) oncogenes, were injected subcutaneously into fat-1 or wild type mice. Tumor growth and angiogenesis of the TC-1 tumor were significantly suppressed in fat-1 compared to wild type mice. cDNA microarray of the tumors derived from fat-1 and wild type mice revealed that MMP-9 is downregulated in fat-1 mice. Immunohistochemical study demonstrated immunoreactivity for MMP-9 in the tumor stromal fibroblasts was diffusely positive in wild type whereas focal in fat-1 mice. MMP-9 was expressed in primary cultured fibroblasts isolated from fat-1 and wild type mice but was not expressed in TC-1 cells. Co-culture of fibroblasts with TC-1 cells enhanced the expression and the proteinase activity of MMP-9, although the protease activity of MMP-9 in fat-1-derived fibroblasts was lower than that in wild type fibroblasts. Our data suggests that omega-3 PUFAs suppress MMP-9 induction and tumor angiogenesis. These findings may provide insight into mechanisms by which omega-3 PUFAs exert anti-tumor effects by modulating tumor microenvironment.

Characterization of synergistic anti-cancer effects of docosahexaenoic acid and curcumin on DMBA-induced mammary tumorigenesis in mice

BACKGROUND

The major obstacles to the successful use of individual nutritional compounds as preventive or therapeutic agents are their efficacy and bioavailability. One approach to overcoming this problem is to use combinations of nutrients to induce synergistic effects. The objective of this research was to investigate the synergistic effects of two dietary components: docosahexaenoic acid (DHA), an omega-3 fatty acid present in cold-water fish, and curcumin (CCM), an herbal nutrient present in turmeric, in an in vivo model of DMBA-induced mammary tumorigenesis in mice.

METHODS

We used the carcinogen DMBA to induce breast tumors in SENCAR mice on control, CCM, DHA, or DHA + CCM diets. Appearance and tumor progression were monitored daily. The tumors were harvested 15 days following their first appearance for morphological and immunohistological analysis. Western analysis was performed to determine expression of maspin and survivin in the tumor tissues. Characterization of tumor growth was analyzed using appropriate statistical methods. Otherwise all other results are reported as mean ± SD and analyzed with one-way ANOVA and Tukey's post hoc procedure.

RESULTS

Analysis of gene microarray data indicates that combined treatment with DHA + CCM altered the profile of "PAM50" genes in the SK-BR-3 cell line from an ER⁻/Her-2⁺ to that resembling a "normal-like" phenotype. The in vivo studies demonstrated that DHA + CCM treatment reduced the incidence of breast tumors, delayed tumor initiation, and reduced progression of tumor growth. Dietary treatment had no effect on breast size development, but tumors from mice on a control diet (untreated) were less differentiated than tumors from mice fed CCM or DHA + CCM diets. The synergistic effects also led to increased expression of the pro-apoptotic protein, maspin, but reduced expression of the anti-apoptotic protein, survivin.

CONCLUSIONS

The SK-BR-3 cells and DMBA-induced tumors, both with an ER⁻ and Her-2⁺ phenotype, were affected by the synergistic interaction of DHA and CCM. This suggests that the specific breast cancer phenotype is an important factor for predicting efficacy of these nutraceuticals. The combination of DHA and CCM is potentially a dietary supplemental treatment for some breast cancers, likely dependent upon the molecular phenotype of the cancer.

The multifaceted effects of omega-3 polyunsaturated Fatty acids on the hallmarks of cancer

Omega-3 polyunsaturated fatty acids, in particular eicosapentaenoic acid, and docosahexaenoic acid have been shown to have multiple beneficial antitumour actions that affect the essential alterations that dictate malignant growth. In this review we explore the putative mechanisms of action of omega-3 polyunsaturated fatty acid in cancer protection in relation to self-sufficiency in growth signals, insensitivity to growth-inhibitory signals, apoptosis, limitless replicative potential, sustained angiogenesis, and tissue invasion, and how these will hopefully translate from bench to bedside.

Synthesis and characterization of novel n-9 fatty acid conjugates possessing antineoplastic properties

The present study enumerates the synthesis, spectroscopic characterization, and evaluation of anticancer potential of esters of two n-9 fatty acids viz., oleic acid (OLA) and ricinoleic acid (RCA) with 2,4- or 2,6-diisopropylphenol. The synthesis strategy involved esterification of the hydroxyl group of diisopropylphenol (propofol) to the terminal carboxyl group of n-9 fatty acid. The synthesized propofol-n-9 conjugates having greater lipophilic character were tested initially for cytotoxicity in-vitro. The conjugates showed specific growth inhibition of cancer cell lines whereas no effect was observed in normal cells. In general, pronounced growth inhibition was found against the human skin malignant melanoma cell line (SK-MEL-1). The anticancer potential was also determined by testing the effect of these conjugates on cell migration, cell adhesion and induction of apoptosis in SK-MEL-1 cancer cells. Propofol-OLA conjugates significantly induced apoptosis in contrast to propofol-RCA conjugates which showed only weak signals for cytochrome c. Conclusively, the synthesized novel ester conjugates showed considerable moderation of anti-tumor activity. This preliminary study places in-house synthesized conjugates into the new class of anticancer agents that possess selectivity toward cancer cells over normal cells.

Polyunsaturated fatty acid metabolism in prostate cancer

Polyunsaturated fatty acids (PUFA) play important roles in the normal physiology and in pathological states including inflammation and cancer. While much is known about the biosynthesis and biological activities of eicosanoids derived from ω6 PUFA, our understanding of the corresponding ω3 series lipid mediators is still rudimentary. The purpose of this review is not to offer a comprehensive summary of the literature on fatty acids in prostate cancer but rather to highlight some of the areas where key questions remain to be addressed. These include substrate preference and polymorphic variants of enzymes involved in the metabolism of PUFA, the relationship between de novo lipid synthesis and dietary lipid metabolism pathways, the contribution of cyclooxygenases and lipoxygenases as well as terminal synthases and prostanoid receptors in prostate cancer, and the potential role of PUFA in angiogenesis and cell surface receptor signaling.

Human serum-derived hydroxy long-chain fatty acids exhibit anti-inflammatory and anti-proliferative activity

Background

Circulating levels of novel long-chain hydroxy fatty acids (called GTAs) were recently discovered in the serum of healthy subjects which were shown to be reduced in subjects with colorectal cancer (CRC), independent of tumor burden or disease stage. The levels of GTAs were subsequently observed to exhibit an inverse association with age in the general population. The current work investigates the biological activity of these fatty acids by evaluating the effects of enriched human serum extracts on cell growth and inflammation.

Methods

GTAs were extracted from commercially available bulk human serum and then chromatographically separated into enriched (GTA-positive) and depleted (GTA-negative) fractions. SW620, MCF7 and LPS stimulated RAW264.7 cells were treated with various concentrations of the GTA-positive and GTA-negative extracts, and the effects on cell growth and inflammation determined.

Results

Enriched fractions resulted in poly-ADP ribose polymerase (PARP) cleavage, suppression of NFκB, induction of IκBα, and reduction in NOS2 mRNA transcript levels. In RAW264.7 mouse macrophage cells, incubation with enriched fractions prior to treatment with LPS blocked the induction of several pro-inflammatory markers including nitric oxide, TNFα, IL-1β, NOS2 and COX2.

Conclusions

Our results show that human serum extracts enriched with endogenous long-chain hydroxy fatty acids possess anti-inflammatory and anti-proliferative activity. These findings support a hypothesis that the reduction of these metabolites with age may result in a compromised ability to defend against uncontrolled cell growth and inflammation, and could therefore represent a significant risk for the development of CRC.

A synergistic antiproliferation effect of curcumin and docosahexaenoic acid in SK-BR-3 breast cancer cells: unique signaling not explained by the effects of either compound alone

BACKGROUND

Breast cancer is a collection of diseases in which molecular phenotypes can act as both indicators and mediators of therapeutic strategy. Therefore, candidate therapeutics must be assessed in the context of multiple cell lines with known molecular phenotypes. Docosahexaenoic acid (DHA) and curcumin (CCM) are dietary compounds known to antagonize breast cancer cell proliferation. We report that these compounds in combination exert a variable antiproliferative effect across multiple breast cell lines, which is synergistic in SK-BR-3 cells and triggers cell signaling events not predicted by the activity of either compound alone.

METHODS

Dose response curves for CCM and DHA were generated for five breast cell lines. Effects of the DHA+ CCM combination on cell proliferation were evaluated using varying concentrations, at a fixed ratio, of CCM and DHA based on their individual ED₅₀. Detection of synergy was performed using nonlinear regression of a sigmoid dose response model and Combination Index approaches. Cell molecular network responses were investigated through whole genome microarray analysis of transcript level changes. Gene expression results were validated by RT-PCR, and western blot analysis was performed for potential signaling mediators. Cellular curcumin uptake, with and without DHA, was analyzed via flow cytometry and HPLC.

RESULTS

CCM+DHA had an antiproliferative effect in SK-BR-3, MDA-MB-231, MDA-MB-361, MCF7 and MCF10AT cells. The effect was synergistic for SK-BR-3 (ER⁻ PR⁻ Her2⁺) relative to the two compounds individually. A whole genome microarray approach was used to investigate changes in gene expression for the synergistic effects of CCM+DHA in SK-BR-3 cells lines. CCM+DHA triggered transcript-level responses, in disease-relevant functional categories, that were largely non-overlapping with changes caused by CCM or DHA individually. Genes involved in cell cycle arrest, apoptosis, inhibition of metastasis, and cell adhesion were upregulated, whereas genes involved in cancer development and progression, metastasis, and cell cycle progression were downregulated. Cellular pools of PPARγ and phospho-p53 were increased by CCM+DHA relative to either compound alone. DHA enhanced cellular uptake of CCM in SK-BR-3 cells without significantly enhancing CCM uptake in other cell lines.

CONCLUSIONS

The combination of DHA and CCM is potentially a dietary supplemental treatment for some breast cancers, likely dependent upon molecular phenotype. DHA enhancement of cellular curcumin uptake is one potential mechanism for observed synergy in SK-BR-3 cells; however, transcriptomic data show that the antiproliferation synergy accompanies many signaling events unique to the combined presence of the two compounds.

Antimutagenicity and antiproliferative studies of lipidic extracts from white shrimp (Litopenaeus vannamei)

An organic extract from fresh shrimp (Litopenaeus vannamei) was studied for antimutagenic and antiproliferative properties using Salmonella typhimurium tester strains TA98 and TA100 with metabolic activation (S9) and a cancer cell line (B-cell lymphoma), respectively. Shrimp extract was sequentially fractionated by thin layer chromatography (TLC) and each fraction was tested for antimutagenic and antiproliferative activities. Crude organic extracts obtained from shrimp reduced the number of revertants caused by aflatoxina B₁, showing a dose-response type of relationship. Sequential TLC fractionation of the active extracts produced several antimutagenic and/or antiproliferative fractions. These results suggested that the lipid fraction of the tested species contained compounds with chemoprotective properties that reduce the mutagenicity of AFB₁ and proliferation of a cancer cell line.

Docosahexaenoic acid metabolome in neural tumors: identification of cytotoxic intermediates

Docosahexaenoic acid (DHA) protects neural cells from stress-induced apoptosis. On the contrary, DHA exerts anticancer effects, and we have shown that DHA induces apoptosis in neuroblastoma, an embryonal tumor of the sympathetic nervous system. We now investigate the DHA metabolome in neuroblastoma using a targeted lipidomic approach in order to elucidate the mechanisms behind the DHA-induced cytotoxicity. LC-MS/MS analysis was used to identify DHA-derived lipid mediators in neuroblastoma cells. Presence of the 15-lipoxygenase enzyme was investigated using immunoblotting, and cytotoxic potency of DHA and DHA-derived compounds was compared using the MTT cell viability assay. Neuroblastoma cells metabolized DHA to 17-hydroxydocosahexaenoic acid (17-HDHA) via 17-hydroperoxydocosahexaenoic acid (17-HpDHA) through 15-lipoxygenase and autoxidation. In contrast to normal neural cells, neuroblastoma cells did not produce the anti-inflammatory and protective lipid mediators, resolvins and protectins. 17-HpDHA had significant cytotoxic potency, with an IC(50) of 3-6 microM at 72 h, compared to 12-15 microM for DHA. alpha-Tocopherol protected cells from 17-HpDHA-induced cytotoxicity. DHA inhibited secretion of prostaglandin-E(2) and augmented the cytotoxic potency of the cyclooxygenase-2-inhibitor celecoxib. The cytotoxic effect of DHA in neuroblastoma is mediated through production of hydroperoxy fatty acids that accumulate to toxic intracellular levels with restricted production of its products, resolvins and protectins.-Gleissman, H., Yang, R., Martinod, K., Lindskog, M., Serhan, C. N., Johnsen, J. I., Kogner, P. Docosahexaenoic acid metabolome in neural tumors: identification of cytotoxic intermediates.

Chemopreventive and renal protective effects for docosahexaenoic acid (DHA): implications of CRP and lipid peroxides

Background

The fish oil-derived ω-3 fatty acids, like docosahexanoic (DHA), claim a plethora of health benefits. We currently evaluated the antitumor effects of DHA, alone or in combination with cisplatin (CP) in the EAC solid tumor mice model, and monitored concomitant changes in serum levels of C-reactive protein (CRP), lipid peroxidation (measured as malondialdehyde; MDA) and leukocytic count (LC). Further, we verified the capacity of DHA to ameliorate the lethal, CP-induced nephrotoxicity in rats and the molecular mechanisms involved therein.

Results

EAC-bearing mice exhibited markedly elevated LC (2-fold), CRP (11-fold) and MDA levels (2.7-fold). DHA (125, 250 mg/kg) elicited significant, dose-dependent reductions in tumor size (38%, 79%; respectively), as well as in LC, CRP and MDA levels. These effects for CP were appreciably lower than those of DHA (250 mg/kg). Interestingly, DHA (125 mg/kg) markedly enhanced the chemopreventive effects of CP and boosted its ability to reduce serum CRP and MDA levels. Correlation studies revealed a high degree of positive association between tumor growth and each of CRP (r = 0.85) and leukocytosis (r = 0.89), thus attesting to a diagnostic/prognostic role for CRP.

On the other hand, a single CP dose (10 mg/kg) induced nephrotoxicity in rats that was evidenced by proteinuria, deterioration of glomerular filtration rate (GFR, -4-fold), a rise in serum creatinine/urea levels (2–5-fold) after 4 days, and globally-induced animal fatalities after 7 days. Kidney-homogenates from CP-treated rats displayed significantly elevated MDA- and TNF-α-, but reduced GSH-, levels. Rats treated with DHA (250 mg/kg, but not 125 mg/kg) survived the lethal effects of CP, and showed a significant recovery of GFR; while their homogenates had markedly-reduced MDA- and TNF-α-, but -increased GSH-levels. Significant association was detected between creatinine level and those of MDA (r = 0.81), TNF-α ) r = 0.92) and GSH (r = -0.82); implying causal relationships.

Conclusion

DHA elicited prominent chemopreventive effects on its own, and appreciably augmented those of CP as well. The extent of tumor progression in various mouse groups was highly reflected by CRP levels (thus implying a diagnostic/prognostic role for CRP). Further, this study is the first to reveal that DHA can obliterate the lethal CP-induced nephrotoxicity and renal tissue injury. At the molecular level, DHA appears to act by reducing leukocytosis, systemic inflammation, and oxidative stress.

Sensitization by dietary docosahexaenoic acid of rat mammary carcinoma to anthracycline: a role for tumor vascularization

PURPOSE

To investigate whether dietary docosahexaenoic acid (DHA), a peroxidizable polyunsaturated omega-3 fatty acids, sensitizes rat mammary tumors to anthracyclines and whether its action interferes with tumor vascularization, a critical determinant of tumor growth.

EXPERIMENTAL DESIGN

Female Sprague-Dawley rats were initiated by N-methylnitrosourea to develop mammary tumors and then assigned to a control group (n = 18), receiving a supplementation of palm oil, or to a DHA group (n = 54), supplemented with a microalgae-produced oil (DHASCO, 1.5 g/d). The DHA group was equally subdivided into three subgroups with addition of different amounts of alpha-tocopherol. Epirubicin was injected weekly during 6 weeks after the largest tumor reached 1.5 cm(2), and subsequent changes in the tumor surface were evaluated. Tumor vascularization was assessed by power Doppler sonography before and during chemotherapy.

RESULTS

DHA and alpha-tocopherol were readily absorbed and incorporated into rat tissues. Epirubicin induced a 45% mammary tumor regression in the DHA-supplemented group, whereas no tumor regression was observed in the control group. In the DHA group, before chemotherapy was initiated, tumor vascular density was 43% lower than in the control group and remained lower during chemotherapy. Enhancement of epirubicin efficacy by DHA was abolished in a dose-dependent manner by alpha-tocopherol, and the same trend was observed for DHA-induced reduction in tumor vascular density.

CONCLUSIONS

Dietary DHA supplementation led to a reduction in tumor vascularization before the enhancement of any response to anthracyclines, suggesting that DHA chemosensitizes mammary tumors through an inhibition of the host vascular response to the tumor.

Docosahexaenoic acid induces ciap1 mRNA and protects human endothelial cells from stress-induced apoptosis

Induction of apoptosis represents a potential reaction of endothelial cells (ECs) after injury of the vascular endothelium. Beneficial effects of n-3 polyunsaturated fatty acids (PUFAs) in vascular diseases are widely recognized although the responsible mechanisms are not fully understood. Because it is not known whether PUFAs modulate EC apoptosis, we investigated the effects of n-3 and n-6 PUFAs on 4-hydroxynonenal (HNE)-induced EC apoptosis by annexin V staining and caspase-3 activation assays. Pretreatment with the n-3 fatty acid docosahexaenoic acid (DHA) reduced HNE-induced EC apoptosis. DHA-treated cells did not show the pronounced drop in intracellular GSH after HNE exposure seen in vehicle- or n-6 arachidonic acid-treated cells. This is most likely due to increased GSH levels in DHA-treated cells. Furthermore, DHA pretreatment increased ciap1 mRNA levels and transfection of cIAP1 small interfering RNA abolished the protective effect of DHA in HNE-induced apoptosis in HUVECs. Thus pretreatment of HUVECs with DHA reduces HNE-induced oxidative stress and apoptosis, and the protective effects of DHA seem to be dependent on cIAP1. The results provide a possible new mechanism for the atheroprotective effects of n-3 fatty acids in vascular disease.

Anticancer properties of propofol-docosahexaenoate and propofol-eicosapentaenoate on breast cancer cells

Introduction

Epidemiological evidence strongly links fish oil, which is rich in docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), with low incidences of several types of cancer. The inhibitory effects of omega-3 polyunsaturated fatty acids on cancer development and progression are supported by studies with cultured cells and animal models. Propofol (2,6-diisopropylphenol) is the most extensively used general anesthetic–sedative agent employed today and is nontoxic to humans at high levels (50 μg/ml). Clinically relevant concentrations of propofol (3 to 8 μg/ml; 20 to 50 μM) have also been reported to have anticancer activities. The present study describes the synthesis, purification, characterization and evaluation of two novel anticancer conjugates, propofol-docosahexaenoate (propofol-DHA) and propofol-eicosapentaenoate (propofol-EPA).

Methods

The conjugates linking an omega-3 fatty acid, either DHA or EPA, with propofol were synthesized and tested for their effects on migration, adhesion and apoptosis on MDA-MB-231 breast cancer cells.

Results

At low concentrations (25 μM), DHA, EPA or propofol alone or in combination had minimal effect on cell adhesion to vitronectin, cell migration against serum and the induction of apoptosis (only 5 to 15% of the cells became apoptotic). In contrast, the propofol-DHA or propofol-EPA conjugates significantly inhibited cell adhesion (15 to 30%) and migration (about 50%) and induced apoptosis (about 40%) in breast cancer cells.

Conclusion

These results suggest that the novel propofol-DHA and propofol-EPA conjugates reported here may be useful for the treatment of breast cancer.

n-3 PUFAs reduce VEGF expression in human colon cancer cells modulating the COX-2/PGE2 induced ERK-1 and -2 and HIF-1alpha induction pathway

n-3 Polyunsaturated fatty acids (PUFAs) inhibit the development of microvessels in mammary tumors growing in mice. Human colorectal tumors produce vascular endothelial growth factor (VEGF) whose expression is up-regulated in tumor cells by both cyclooxygenase-2 (COX-2) and PGE(2) and directly correlated to neoangiogenesis and clinical outcome. The goal of this study was to examine the capability of n-3 PUFAs to regulate VEGF expression in HT-29 human colorectal cells in vitro and in vivo. Constitutive VEGF expression was augmented in cultured HT-29 cells by serum starvation and the effects of eicosapentaenoic (EPA) or docosahexaenoic acid (DHA) on VEGF, COX-2, phosphorylated extracellular signal-regulated kinase (ERK)-1 and -2 and hypoxia-inducible-factor 1-alpha (HIF-1alpha) expression and PGE(2) levels were assessed. Tumor growth, VEGF, COX and PGE(2) analysis were carried out in tumors derived from HT-29 cells transplanted in nude mice fed with either EPA or DHA. Both EPA and DHA reduced VEGF and COX-2 expression and PGE(2) levels in HT-29 cells cultured in vitro. Moreover, they inhibited ERK-1 and -2 phosphorylation and HIF-1alpha protein over-expression, critical steps in the PGE(2)-induced signaling pathway leading to the augmented expression of VEGF in colon cancer cells. EPA always showed higher efficacy than DHA in vitro. Both fatty acids decreased the growth of the tumors obtained by inoculating HT-29 cells in nude mice, microvessel formation and the levels of VEGF, COX-2 and PGE(2) in tumors. The data provide evidence that these n-3 PUFAs are able to inhibit VEGF expression in colon cancer cells and suggest that one possible mechanism involved may be the negative regulation of the COX-2/PGE(2) pathway. Their potential clinical application as anti-angiogenic compounds in colon cancer therapy is proposed.

Red oil A5 inhibits proliferation and induces apoptosis in pancreatic cancer cells

AIM: To study the effect of red oil A5 on pancreatic cancer cells and its possible mechanisms.

METHODS: Effect of different concentrations of red oil A5 on proliferation of three pancreatic cancer cell lines, AsPC-1, MiaPaCa-2 and S2013, was measured by ³H-methyl thymidine incorporation. Time-dependent effects of 1:32 000 red oil A5 on proliferation of three pancreatic cancer cell lines, were also measured by ³H-methyl thymidine incorporation, and Time-course effects of 1:32 000 red oil A5 on cell number. The cells were counted by Z1-Coulter Counter. Flow-cytometric analysis of cellular DNA content in the control and red oil A5 treated AsPC-1, MiaPaCa-2 and S2013 cells, were stained with propidium iodide. TUNEL assay of red oil A5-induced pancreatic cancer cell apoptosis was performed. Western blotting of the cytochrome c protein in AsPC-1, MiaPaCa-2 and S2013 cells treated 24 hours with 1:32 000 red oil A5 was performed. Proteins in cytosolic fraction and in mitochondria fraction were extracted. Proteins extracted from each sample were electrophoresed on SDS-PAGE gels and then were transferred to nitrocellulose membranes. Cytochrome c was identified using a monoclonal cytochrome c antibody. Western blotting of the caspase-3 protein in AsPC-1, MiaPaCa-2 and S2013 cells treated with 1:32 000 red oil A5 for 24 hours was carried out. Proteins in whole cellular lysates were electrophoresed on SDS-PAGE gels and then transferred to nitrocellulose membranes. Caspase-3 was identified using a specific antibody. Western blotting of poly-ADP ribose polymerase (PARP) protein in AsPC-1, MiaPaCa-2 and S2013 cells treated with 1:32 000 red oil A5 for 24 hours was performed. Proteins in whole cellular lysates were separated by electrophoresis on SDS-PAGE gels and then transferred to nitrocellulose membranes. PARP was identified by using a monoclonal antibody.

RESULTS: Red oil A5 caused dose- and time-dependent inhibition of pancreatic cancer cell proliferation. Propidium iodide DNA staining showed an increase of the sub-G0/G1 cell population. The DNA fragmentation induced by red oil A5 in these three cell lines was confirmed by the TUNEL assay. Furthermore, Western blotting analysis indicated that cytochrome c was released from mitochondria to cytosol during apoptosis, and caspase-3 was activated following red oil A5 treatment which was measured by procaspase-3 cleavage and PARP cleavage.

CONCLUSION: These findings show that red oil A5 has potent anti-proliferative effects on human pancreatic cancer cells with induction of apoptosis in vitro.

Oil A induces apoptosis of pancreatic cancer cells via caspase activation, redistribution of cell cycle and GADD expression

AIM

To explore the mechanisms of effects of oil A on apoptosis of human pancreatic cancer cells.

METHODS

Cellular DNA content was analyzed by flow cytometry. Western blotting was used for caspase-3 and PARP, caspase-7, caspase-9, cytochrome c, Bcl-2, Bax, Mcl-1, cyclinA, cyclin B1, cyclin D1, cyclin E, CDK2, CDK4, CDK6, P21, P27, GADD45, GADD153.

RESULTS

The caspase-3, caspase-7, and caspase-9 activities were significantly increased as well as the cleavage of caspase-3, downstream substrate poly-ADP ribose polymerase (PARP) was induced. The amount of cytochrome c in the cytosolic fraction was increased, while the amount of cytochrome c in the mitochondrial fraction was decreased after oil A treatment. The anti-apoptosis proteins Bcl-2 and Mcl-1 were decreased in parallel and Bax increased, indicating that Bcl-2 family proteins-mitochondria-caspase cascade was responsible for oil-induced apoptosis. The proportion of cells in the G0/G1 decreased in MiaPaCa-2 and AsPC-1 cells after the treatment of oil A for 24 hours. The number of cells in S phase was increased in two cancer cell lines at 24 hours. Therefore, cells were significantly accumulated in G2/M phase. The cells with a sub-G0/G1 DNA content, a hallmark of apoptosis, were seen at 24 hours both in MiaPaCa-2 and AsPC-1 cells following exposure to oil A. The expression of cyclin A and cyclin B1 was slightly decreased and cyclin D1 levels were markedly lowered in MiaPaCa-2 cells. The expression of cyclin A and cyclin B1 was markedly decreased and cyclin D1 levels were slightly lowered in AsPC-1 cells, while cyclin E was not affected and the levels of CDK2, CDK4, and CDK6 were unchanged in MiaPaCa-2 and AsPC-1 cells. In response to oil A, P21 expression was increased, but P27 expression was not affected. The expression of both GADD45 and GADD153 was increased in two cell lines following oil A treatment.

CONCLUSION

Oil A induces apoptosis of pancreatic cancer cells via activating caspase cascade, modifying cell cycle progress and changing cell cycle-regulating proteins and GADD expression.